Hi mark290638-rail, the creation of a new '''default-release''' profile should be a one-time event. If you simply use Firefox and let it update automatically, your profile should remain stable and no new profile needs to be created. From time to time, Firefox may suggest a tune-up, meaning a Refresh. If you don't want any settings changes, don't do a Refresh. Using an installer you download could cause Firefox to want to create a new profile. I don't have a clear understanding of when Firefox might say that your current profile doesn't work with the new version you installed. Hopefully you won't end up in this situation because you can use the built-in updater. <blockquote>1. a. In simple terms, what constitutes a new installation and when is one created? whenever Firefox is restarted? whenever Firefox is updated? When I reboot my computer? Or ????</blockquote> Usually this would refer to running a Firefox installer, particularly if it creates a new program folder (for example, if you install Firefox Developer Edition alongside the normal version). <blockquote>b. How can I avoid the creation of new installations? </blockquote> Don't run any Firefox installers. <blockquote>2.a Help paragraph on what my options are regarding the introduction of dedicated profiles says that I can keep the data the same in all profiles by syncing them-How exactly do I do that?</blockquote> I'll give you a link to an article about Sync, but unless you plan to use multiple profiles, then it won't do much because you have to use a profile for Sync to run. [[How do I set up Sync on my computer?]] <blockquote>3. To be sure I do not lose access to, for example Bookmarks I have set up, do I regularly have to go to the Profile Manager and delete all of the profiles that Firefox has created except for the one default one that I want to keep?</blockquote> Please do not delete anything. You can just switch to the one that works best for you. Maybe this will help: If you are not seeing all the data you think you have saved in Firefox, you may be using the wrong profile. Here's how to check that: '''Profile Manager Page''' Inside Firefox, type or paste '''about:profiles''' in the address bar and press Enter/Return to load it. This page should list at least one profile and could list many. (Each profile has two folders and one or more buttons. Do not use any Remove buttons!) The profile that Firefox is currently using will have this: '''This is the profile in use and it cannot be deleted.''' Do you have another profile named '''default''' or default-''longnumber'' listed on this page? If so, you can check whether it is the one you were using recently by clicking its '''Launch profile in new browser''' button. If it isn't what you want, simply close that new window. If it IS what you want, back on the about:profiles page, click the '''Set as default profile''' button for that profile so Firefox uses it automatically at the next startup. Hope that helps.

Thanks for the help!