Shared note opened wrong account now Gmail won’t show under default in Notes

Someone shared a note with me and when i opened it, my notes app was signed in on a different account. Theb when i went to my settings app to change it back the gmail option wouldn’t pop up under the default account setting even though I have notes enabled? Please help im so lost

[Re-Titled by Moderator]

Original Title: How do I sign into my gmail notes account?