Hello Dan.
Thank you for contacting AVG Community Support.
It is recommended to install AVG Antivirus in the Operating system installed drive to protect the computer hence there is no option to change the drive.
If you need any other help with AVG please feel free to reach us again.
Thank you.
The offline installer does not allow changing the destination drive or folder. The regular installer allows changing it. Is this by design? If it is, what is the reason? If it is not by design, will it be changed?
We'd like to clarify that the offline installer should allow you to change the destination folder, during the installation process.
You can try clicking on 'Custom installation' to check if you're able to change the destination folder.