Only account admins can edit account permissions. If you're an admin, tap on the Settings button in the upper right corner of your account. Tap on Manage Members & Permissions, then tap on Member Permissions. The permissions are:
Transfer Money Out - Can other users withdraw out of the account?
Spend with Debit Card - Can other users spend with an account debit card?
View Transactions - Can other users view transactions?
Invite Others - Can other users invite others into the account?
Daily Spending Limit - What is the maximum amount that can be spent out of the account each day?