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:





