How can I add another administrator to this account? Do the administrators have access to all forms?

Hello dballintyn,

I am not sure if I have understood your requirement correctly. It seems you want to give someone access to your forms. Is that correct?

You can add sub users in your account and share desired form or all forms with that user. The following guide should help you how to create sub user account and share forms:  http://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-Account-User 

Hope this helps.

Do get back to us if you have any questions.

Thank you!