Install, or change things on a windows that is installed on an external harddrive?

my friend lend me his C:// external harddrive from his desktop computer to let me change his resolution and try to install things on it, rite now i have it connected to my laptop but im using MY window, can i be able to change or install things in his windows when im using my windows? or i need to boot to his window to do it?Install, or change things on a windows that is installed on an external harddrive?Yes to make changes you will need to boot to his Window and further you can make the changes easily.