Firefox opens everything in current window, killing it. Using back button I find previous page (one only) reloaded, losing all information
Why are you eliminating any way to open pages in new windows? That's a deal breaker for me. I'm sick and tired of opening tabs then having to use the context menu to move them to a new window. The browser now dumps every open link into the same window, killing any information in the previous window if you use the back button to go back to it.
Type about:preferences#general<enter> in the address box. Under Tabs, mark/unmark Open New Windows In A New Tab Instead.
This is a long response, so I apologize, but it needs to be long to address these kinds of suggestions. While I appreciate the response and your suggestion, my first question about it is "Why would I do that?" If you read my post, you will see that I DO NOT WANT to open any links in a new tab. But secondary, that is not the way the choice is even worded in about:preferences#general in Firefox v.96. It is worded exactly the opposite: "Open links in tabs instead of new windows." Which is exactly what it I do not want it to do, along with opening the links in the same window and closing what was in that window. You have indicated to mark or unmark that choice, and I have done both, without any change in the program's performance. It still continues to open new links selected, in the same window and NOT in a new tab, and NOT in a new window.
I WANT to open new links in a new window, NOT a tab, and I REALLY do not want it to open links in the same window, replacing the page in that window (which erases all information I may have entered in the window it replaces). Interestingly also is the fact that at about the same time that this problem came up, I also noted the sudden disappearance of "Open Link In New Window" from the right click drop down context menu, ONLY in Firefox. Coincidence?
Since inevitably the next standard non-answer in forums that someone always makes is "Why would you want to do that?" It doesn't matter why, but to answer it ahead of time before the inevitable, I am not wanting to open windows in a new tab, because I often I want two windows opened up at the same time so that I can work back in forth in both. (like writing an article in an online text box in one window, while copying and pasting quotes from another in the other window). So opening something in a new tab doesn't work for my application.
I might add, that what I am wanting to do is NOT unusual or abnormal, as even the default choices in about:preferences state clearly the choice "Open links in tabs instead of new windows," which clearly implies that the default would be to open them in new windows.
I spent the money to upgrade to a much wider monitor, specifically to be able to do this, and instead of being able to, the browser (and most people on support forums) seem to be so absolutely focused on wanting to open links in new tabs, (because that's what THEY want to do) that they completely ignore what I am wanting to do.
So for the benefit of others who may land on this thread and post the same kinds of suggestions, let's clear the slate again, and note that what I am wanting to do IS the default, and that for reasons unknown, after the last half dozen Firefox updates, and with no changes or additions initiated to the program by myself, it has suddenly not only stopped doing what it did by default, but is also now doing something it did not do before, and which is NOT what was default behavior, that of opening new links in the same window and replacing the open page that was in that window, essentially closing it, AND eliminating the choice of "Open Link in New Window" in the drop-down right click context menu. That suggests a coordinated effort to actually STOP me from doing what was once default behavior. The fact that you seem to experience Firefox differently than I do, indicates the possibility that the new "normandy" back door that allows Mozilla to change the function of the browser without my knowledge, may be involved. That is somewhat confirmed by settings in about:config, which are now highlighted in bold face type indicating they were changed locally on my copy of the browser, and not by me. I can almost see the developers scurrying to get rid of that tip-off that they didn't think about.....
To head off the next suggestion that it isn't a Mozilla problem, it occurs only in Mozilla, not other browsers like Brave or Vivaldi, both of which are Chromium based, nor Edge (MS), nor IE. Also, I have Windows 10 locked to prohibit MS from making any changes to it, so it is not due to any changes in my OS. This was done when I installed the latest update last year, because of their announcement that they were introducing W11, and in no way did I want them installing the "update" that they tried to install, which "preps" my machine for an automatic download and installation by them of W11, (which they already tried to install). W11 is the worst version they have come out with to date, and when W10 is no longer supported, I will likely switch to Linux and go back to the dark ages with command lines, just to get away from Microsoft.
So Firefox continues to open new links in the same window I am already in, regardless of how I set it in either preferences OR even the values inserted in about:config and browser.link.open_newwindow, as suggested in a ghacks article (link below) about this very issue.
It's interesting to me that even the ghacks article, seems to be in a different dimension from me, because it also has the problem exactly backwards from what I am experiencing in the browser. So let's start from the reality that despite what the browser is supposed to do, it is not doing that, and is instead doing what IT wants to do. AND let's for just the moment stop assuming that the problem is in something I am doing wrong. I did nothing to the browser recently to cause this change, and it is a change, and it came about starting about 6 updates ago (Firefox automatic updates).
The article addresses an additional group of settings under about:config including an update about the behavior of the browser, and provides additional values to set:
It says to open about:config then browser.link.open_newwindow. It goes on to say the default value of that entry is 3 which opens links that would normally open in a new window in a new tab. Mine wasn't set to 3 it was set to 1. And it was in bold face type, indicating it had been changed by someone. And that is the behavior I observed, under "Value of 1" below:"To force Firefox to open links (no matter if they have been designed to open in a new tab or window) in the same tab one would need to change the value to  which will open all links that would normally open in a new window in the same tab. <<<<<THAT is apparently what it is doing....which, as I said, replaces what is in that tab or window. Changing the value to  would open new windows in a new window (duh). <<<[ The "(duh)" is the author's comment not mine.]</em>
Value of 1: Opens links that would normally open in a new tab or new window in the current tab or window Value of 2: Open links that would normally open in a new window, in a new window Value of 3: Open links that would normally open in a new window in a new tab in the current window"
Changing the setting now to 0, 1, 2, or 3 makes zero difference in the behavior of the browser, nor do changes listed in the same article under "Update" and "Update 2."
I have also noted and neutralized "normandy" and related "studies" settings that seem to have been changed (and not by me) to override my settings, as indicated by them being in bold faced type, and reading on several forums, that Mozilla is using those tools to experiment selectively with the settings of just "certain users" without having to release updates that apply to all users. I do not wish for Mozilla to be changing my settings un-announced and behind my back, OR providing telemetry information to others, especially Google.
Also note that ALL of this began occurring only after the last half dozen or so updates that have been coming rapid fire from Mozilla. Prior to a couple months ago, I was not experiencing this problem. Mozilla has long had a record of constantly fiddling with its browser, causing more problems, then fiddling with the problems it caused until they break it, then releasing a new "update" to repair it. I suspect that they are once again in this mode, since it seems to be something they just always do.
To address in advance the other standard forum trope of "Have you tried removing all add-ons and extensions and/or uninstalling and reinstalling Firefox?", my answer is no, I have done neither, because I had made no changes to the browser in months before it started having the problem, and the only changes that had been made were Firefox automatic updates. I am not going to go through that time wasting process only to find what I usually do, that it makes no difference whatsoever. The fact that I had made no changes or additions to the program, yet it changed, tells me that it the problem resides somewhere in changed made to the core code of the problem by Mozilla. The highlighted settings changes via "normandy" and "studies" indicated also that Mozilla has been in my browser fiddling about with things.
There is something vaguely disturbing to note the inclusion of an api(?) in Firefox, referred to as "normandy" the site of the biggest invasion ever, and the apparently connected "studies" involving scraping of telemetry data off of my machine and "phoning home" with it, but even worse, sending it to the biggest data gatherer on the planet, ABC.
With this problem, I have also been experiencing and noting the return of an absolutely famous Firefox problem, that of overuse of resources, (both memory and CPU) which with my rig, purposely built by me to withstand ANY usage level, is HARD to do, and the corresponding slowness and freezes again, that it has been plagued with for all time eternal, all of these things being exactly why I have repeatedly abandoned the browser, and will likely have to do again.....
I called for more help.
I know this doesn't fix your issue but it is less inconvenient than what you have been doing. You can right-click on a link and select "Open Link in New Window".
It may be that you also need to set the following preference to 1: browser.link.open_newwindow.restriction see https://support.mozilla.org/en-US/questions/1328185#answer-1396449