Hi TexasNative, as a starting point, Firefox scales the user interface and browser content based on your OS "Text Size" setting (commonly 125%). If those are different between your systems, you may notice in icon sizes and spacing.

To clarify something, is the difference on the main toolbar (where you see the web address), or on the tabs bar (where you see site icons + title text), or both?

Or is this a problem on the Windows Taskbar (usually on the bottom of the screen, but could be moved to the top)?

Maybe also check the Density setting in the customize window.

Hi, scher2000

Thanks very much for your response. I am not sure how to determine what the OS “Text Size” settings are on either drive. Would appreciate it if you can tell me how to access this. I installed Windows to the new drive with the same software that I used when I installed it on the original drive, so I would have expected that all of the settings would be the same between the drives. I cannot remember making any specific changes in the settings on the original installation that would affect this.

With respect to differences between the toolbars, I see the problem on both the main toolbars and the Taskbar (mine is at the bottom). I am attaching a pdf showing the two screens. I did notice that on the address bar on the original, there was a small oval with 120% on it to try to see if I could change the settings, it disappeared and I could not get it back. When I re-booted, it came back as 170% and the Google image appeared smaller than it was before (?), but when I again tried to determine how to change the setting, it disappeared.

With respect to the Density setting that cor-el mentioned. I tried changing this setting when I first realized I had a problem. It didn’t help. This setting was the same on both installations.

The Density setting will affect the height of the toolbars and spacing of buttons. If you change from Normal to Compact, the Back button appearance should change from the style shown in the new installation (circled) to the style shown in the old installation. I'm attaching a sample screenshot for reference.

Beyond that the bookmark icons appear a bit larger in the recent installation so if the monitors have the same resolution, there could be a difference in scaling.

If you visit the following page in both Firefoxes and look at the window.devicePixelRatio you can get an idea of your Firefox's scaling:

https://www.jeffersonscher.com/res/resolution.php

If you have 100% zoom on the page, and the value is something other than 1, then that is your Windows Text Size setting. For example, 1.25 indicates your Windows Text Size is 125%.

I checked out your PixelRatio link and found that the two installations have different values (See screen shots). However, I do not have the slightest idea why this would be or how to configure the new installation so it looks like the old one. Any help MUCH appreciated.

I found a tutorial that shows the Small, Medium, Large selections for text size in Windows 8.1, but I can't confirm it myself:

https://www.eightforums.com/threads/dpi-scaling-size-change-for-displays-in-windows-8-1.28310/

Hello, jascher2000.

I finally had time to go check out the link you provided. It WORKED. I had looked at that screen before and tried adjusting the Print Size to Small, but it did not work. I think, maybe, I did not click on the box "Let me choose one scaling level...." and when I exited it, everything went back to the default.

I still cannot understand why it was like this with my first install as I am 90% sure that I never made that change. Of course, I have slept since then (about 4 years ago), so maybe I did and don't remember.

At any rate, the configuration is back to the way I wanted it. I GREATLY APPRECIATE all of your help on this.

Thanks for reporting back. And if you have a free upgrade to Windows 10, you could consider joining many of us on that adventure.

I have considered it, but I like 8.1 and I have seen and heard a lot of unfavorable things about 10, so I am just going to stick with 8.1 for now, Thanks again for your help.