I do not see any issues here, at all (at very least for the Ctrl + Mouse Wheel shortcuts).
Screenshots are from PhpStorm 2020.3.2 on Windows 10 x64.
Settings/Preferences | Keymap
Find the desired action (use the search box to filter available actions)
Right click and choose the right option (Add Mouse Shortcut
):
Use the desired "mouse shortcut" there (press and hold Ctrl and do Mouse Wheel Up):
Apply and start using it: