To add a new admin, you first need to invite them as a regular employee. Providing this is done:
Tap on > Menu > Staff
Tap on > Staff Member's Name You Want To Promote To Admin
Tap on > Settings
Tap on > Promote To Admin
*(Web Version) Click on > Promote
If you ever want to revert the staff member back to an employee role, just follow the same process and Tap on > Revert To Employee
*(Web Version) Click on > Revert
Tap on > Confirm
*(Web Version) Click on > Yes
If you are using the web version it will look like this: