Background
Apple has introduced a security mechanism with macOS 10.14 (Mojave), which requires special access to be granted to remote control applications like TeamViewer.
And macOS 10.15 (Catalina) has strengthened the security and privacy even further and requires additional permissions to be given to TeamViewer in order to control your Mac.
Without this access, TeamViewer users connecting to macOS 10.14 or higher will only be able to view the screen but not control it with their mouse or keyboard.
And TeamViewer users connecting to macOS 10.15 or higher will additionally only be able to view the desktop background and the TeamViewer app, but not any other applications at all.
These additional permissions must be granted locally on the Mac and some of them require admin rights.
How to grant access to TeamViewer on your Mac
If you're starting TeamViewer 14 or higher on your Mac running macOS 10.14 (Mojave) or higher for the first time, you will be prompted with the following dialog:
You can also open this dialog by clicking on Help --> Check system access.
For the Accessibility access, you will need to click the padlock icon in the lower-left corner to make changes. You might be prompted to enter the credentials of an administrator account to continue. To navigate directly use:
Apple Menu > System Preferences > Security & Privacy
(Then choose Accessibility on the sidebar on the left.)
Put a check next to TeamViewer to grant it access:
Repeat the same for Screen Recording.
The permission status can be reviewed under Help -> Check system access at any time.
