FF changes theme to ???????

[tnffuser]

I thought this was resolved.
Each time I set my theme and close FF
Upon opening later somehow FF has changed it to a colorless something.
Maybe it is the default.
How to set FF to keep the theme I choose.

[DanRaisch]

Are you running any sort of clean up utility like Ccleaner?

[tnffuser]

Should have anticipated that question.
No.
Safe mode results in same, and not have not tried new profile.

[WaltS48]

Should have anticipated that question.
No.
Safe mode results in same, and not have not tried new profile.

Well, don't leave us in suspense.

What theme?

One from AMO or one built-in?

I use the Firefox System theme and have no issue on Windows 10 or Fedora Linux.

[jscher2000]

In case this problem is caused by Firefox Sync, you can turn off sync for your theme by toggling the following preference to false in about:config:

services.sync.prefs.sync.extensions.activeThemeID

[tnffuser]

Thank you, will try that.
By the by, currently defaults to system default theme with any assistance on my part.

[tnffuser]

That was he answer.
But beg the question, why is 'services.sync.prefs.sync.extensions.activeThemeID' initially set to True?
Why would the developers not want users to have a choice of themes?
Big Brother knows best?

[dickvl]

If services.sync.prefs.sync.extensions.activeThemeID is set to true then the currently active theme oref (extensions.activeThemeID) is synced among other devices connected to this Sync account.
By setting this pref to false you disable syncing the active theme and each device can have its own theme.

[tnffuser]

Thank you, Sir.
As I do not use sync, setting to false works for me.