Thanks for testing this on two PCs, it helped us find it. When Windows uses a non-Gregorian calendar (Hebrew, for example), Listary built a backup file name from the date that Windows can’t accept, so every save after the first one failed silently. This is fixed in 7.1, and 7.1 also shows a notification if settings ever fail to save. Could you check whether your Windows calendar is set to something other than Gregorian? Download 7.1 here: https://dl.listary.net/v7/Listary.exe and install it over your current version (your settings are kept). Release notes: Listary 7.1 Beta is here. If it still happens, please reply here.