Have you added the guest additions ?
First in the peppermint VM install
sudo apt-get install build-essential dkms
then in the Virtualbox toolbar select:-
Devices > Insert Guest Additions CD ImageThen in the Peppermint VM open the file manager, and in the left-hand pane select "
VBox_GAs"
Then in the right-hand pane select "
Open Autorun Prompt" .. and click "
Run"
Enter your password when prompted
When the terminal says so,
press return to close the windowAnd now reboot the VM