When adding a new card from the home page, the default is ‘image occlusion’ in set A, even though i just added to ‘basic’ in set B.
I am using the newest version of MacOS and the latest anki update. So far I have:
None of these worked 
Any help would be appreciated
When adding, it should default to the current deck and the last-used notetype in that specific deck. Have you checked your preferences?
About the “default deck” option, from Preferences - Anki Manual.
Controls how note types and decks interact. The default of “When adding, default to current deck” means that Anki saves the last-used note type for each deck and selects it again then next time you choose the deck (and, in addition, will start with the current deck selected when choosing Add from anywhere). The other option, “Change deck depending on note type,” saves the last-used deck for each note type (and opens the add window to the last-used note type when you choose Add). This may be more convenient if you always use a single note type for each deck.
The last used deck/note type is updated when you add a card. If you change the deck and close the add window without adding a card, it won’t be saved.
Yes that did not work, unfortunately.
I think maybe you misunderstood how this works. Can you confirm? I said this previously:
You probably last used IO note type in deck A and that’s why IO was selected for deck A. Last used note type is different for each deck, as the manual says.
Yes, but I am confused as to why it keeps defaulting to deck A if i have most recently added to deck B. I am fine with IO being the default for deck A, but I can’t figure out how to change the default from A to B.
Click on deck B. Then try again. Does it work? Adding note to another deck doesn’t “current” it.
I uninstalled Anki, reinstalled it, and redid your instructions, and it worked this time! Must have been a weird bug.
Thank you!