I can't remember whether v7 has the 'organise' tab, but think it did - in which case it replicates your drive directory at the left. If you allowed the computer to use one of the more idiotic classifications like 'pictures'/'all my files', its time to pull your image files into a set of logical folders on the main directory. Hopefully images that you processed will have a .dop file following each RAW file and, whereas the DxO Image Browser may not have record of which were corrected and converted, the corrections will still be there.
I am also pensioner, but keep DxO upto date whatever, but will postpone upgrading to OS Sierra as long as possible. Depends on your other usage and if you had good reason to go to Sierra. If not and its causing havoc and you either have Install file for 10.10 or 10.11 on your computer or downloaded it from Apple store you could consider a backtrack
DxO 11 is leagues ahead of v7 and a good investment for serious photographers. You could think how much you would be saving compared to equivalent upgrade of PS!