If you lost personal data then it is possible that a new default-release profile folder has been created.

You can open the about:profiles page via the location bar to check whether multiple profiles are present and what profile Firefox currently is using.

• Do NOT click any Remove button on this page.
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Firefox 67 and later can use a dedicated profile for each of the Firefox update channels and will lock the profile, so it can only be used by Firefox in a specific installation folder. For Release versions this profile would be a xxxxxxxx.default-release profile, profiles used in older Firefox versions usually used a xxxxxxxx.default profile (a refresh adds a time stamp).

• https://support.mozilla.org/en-US/kb/dedicated-profiles-firefox-installation

https://hacks.mozilla.org/2019/05/firefox-67-dark-mode-css-webrender/

• https://blog.nightly.mozilla.org/2019/01/14/moving-to-a-profile-per-install-architecture/

Hi,

I'm just trying to change my Firefox/Quantum bookmarks toolbar to increase to 3rows. Found the code, and found my profile default file(s).

Problem is . . . there are two . . . don't know which one to use.

Again, just trying to make some changes to my Firefox screen, to make it more usable.

Any idea which one to use?

Thank You!

Firefox last used the default-release folder. This is the preferred folder for Firefox on the release update channel like I posted above.

If there is personal data in the previously used .default folder then you can copy related files form .default to .default-release.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile