In the mobile application: 

For iOS devices: 

1. Open the Zoho One app on your mobile device.
   
2. Tap in the bottom-right corner, then tap Applications.
   
3. Tap on the required app, then tap Add under ADMINS.
   
4. Tap on the user you want to add as an admin, then tap DONE.
   
5. Tap on the appropriate admin role for the user, then tap in the top-right corner.
   
6. Tap Done in the pop-up message that appears.

For Android devices: 

1. Open the Zoho One app on your mobile device.
   
2. Tap in the bottom-right corner, then tap Applications.
   
3. Tap on the required app, then tap under Admins.
   
4. Tap on the user you want to add as an admin, then tap Next.
   
5. Select the appropriate admin role for the user, then tap .