Set permissions to an Access Web App

My assistant built an Access Web App for our department using Office 365.  He sent me the link to test it and I can view it, but not edit it or add data. I am our admin for Office 365.

When he has the database open in the browser, he has no settings.  If he clicks "Back to Site" (in the top left), it takes him back to OneDrive and the database is not listed.

How can we change permissions so I can enter data?

Thanks!