How can I edit the keyboard shortcuts in notes
Go to System Preferences → Keyboard → App Shortcuts.
Click the + to add a new shortcut.
Choose Notes.app, enter ‘Bigger’ as the Menu Title, then set the Keyboard Shortcut ‘⇧⌘=’.
Click Add. The new shortcut will be available for use and will show in the Notes menus as appropriate, under Format → Font → Bigger.