Set File Explorer to Open This PC Instead of Quick Access

In Registry Editor, navigate to the following path:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

In the right pane of Advanced key, double-click on LaunchTo to modify its value data.

Then change LaunchTo DWORD for what you would like:

1 = This PC 2 = Quick access 3 = Downloads