The "Configure Toolbars..." settings are lost between upgrades. The "Text Position" and "Icon Size" settings transfer. Using the same database before and after upgrades. This happened on Ubuntu-Gnome 16.04 x64 between upgrades from 5.3 to 5.4 and 5.4 to 5.5. Also happened on Windows 10 x64 from 5.3 to 5.4 and 5.4 to 5.6. Yes, I skipped 5.5 on Windows 10 but just for curiosity, not to solve any problem.
digiKam 7.0.0 stable release is now published: https://www.digikam.org/news/2020-07-19-7.0.0_release_announcement/ We need a fresh feedback on this file using this version. Best Regards Gilles Caulier
Not reproducible since a very long time. I close this file now.