So when you make your change and you "Store As', you are getting this warning?
Then you press 'Overwrite' and then press 'OK' to leave the Project Preferences (make sure you do not press 'Cancel' or just close the dialogue).
When I do this the changes stick.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11