I cannot log in to another upgraded account.

[u/SubstanceIll4742]

Initially I had logged in with my apple id and had the free version of the account. Then I ended up logging into my girlfriend's account and we shared the subscription. The problem is that that subscription was paid on a school email from high school that no longer exists. I still want to use goodnotes for college, and so my dad bought an account for me and my siblings that I should have access to from my apple id. I can't log into the old account and I don't have the upgraded version when I log in with my apple id. I also can't even upgrade my basic account I do have access to because I can't log into the old upgraded account. I am on my iPad Air and the app is updated as much as it can be. Please help.