Team Users in Account

Hi, I would like to add a user to the team section in an account, but when I try to select a user an the role I want (In this case, owner),  it asks me also for the access to the account, but in that list it doesnt show anything, neither if I change the role, so I went to customize the field and disable the obligatory checkbox, but it doesnt respect it,when I go back and try to select a user, it stills tells me its obligatory.

How can I change this

Thanks