If you can see everything, but cannot control, try the following on the Mac you want to control: 

1. On the Mac that you want to control, go to System Preferences > Security > Privacy > Accessibility.
2. Un-check the TeamViewer and TeamViewer_Desktop entries.
3. Check the TeamViewer and TeamViewer_Desktop entries again.
   
   Also try : Security & Privacy > Screen Recording > TeamViewer

If you still cannot control the Mac and it has “Start with system” turned on:

1. Turn “Start with system” off on the Mac you want to control (Remote Control > Unattended Access).
2. Restart that Mac (just in case).
3. Open TeamViewer again (still with “Start with system” off).

Can you control that Mac now?