[Gabrys1]

Why would you do that? Your firefox config should be kept in .mozilla/firefox (or is it .config/mozilla now?) and simply picked up by the new firefox binary. The only time this doesn't work is when you install an older version whose configuration "format" is not compatible with the newer version's one.

Edit: a sibling commenter just made me aware of the config for the "snappy" version actually resides in another directory. That said you can manually copy the files to the standard place

[bee_rider]

I did that because I didn’t know where the snap files were stored, or that it was different from the normal spot.