This is with all my packs selected that I own. But...Please tell me if I'm understanding you correctly. If If I want to play the save game that I made that only has the base game ...I have to deselect on the main menu again and then play that base game save file.....then when I want to play my other save games that use all my owned packs ...I then need to go back into main menu and select all my packs again??? Is that right?
Correct, pack enabling/disabling is not per save, it's on the game as a whole. Packs you disable will stay disabled no matter what save you open (though if the save previously used a now disabled pack it will give you a warning) and packs that you enable will stay enabled no matter what save you open - which is why you need to select a season with Seasons enabled when opening a save that did not previously use the pack.
Note that even in your screenshot - you're not in any particular save editing those settings, but rather doing so on the main menu.
