The keyboard menu shortcuts for TeXShop can be redefined. To do this, read the comments at the top of the file "KeyEquivalents.plist" and make appropriate changes. To do so, edit the file

~/Library/TeXShop/Menus/KeyEquivalents.plist
with TeXShop. Be sure to edit and save in UTF-8 format if you use Unicode characters.

How do I configure TeXShop?
Redefining Keyboard Menu Shortcuts