Can I change the access to the accounts I manage after signing up?

When I signed up I was offered a list of all the accounts I managed to give access to for various things FB, IG, Ads etc.  I switched them all off apart from my own account initially as I wasn’t sure how i would use it but now I would like to use it for the other accounts I manage, can I go back and change my preferences and allow access to some of the accounts I manage?  At the moment I can add them but they show up as separate accounts which all require a paid scheme. If I change the access would more accounts be under my name? If anyone has any intel on how to do this, that would be great. Many thanks