the following Hotkey Guide gives complete instructions on customizing all hotkeys for wc3, it also includes the customkeys.txt file setup to position all unit spells and abilities on QWER just like in most MobA games, and also includes inventory item keys too!
just click this link here:
https://www.reddit.com/r/WC3/comments/69p3nv/improved_custom_hotkeys_setup_by_wtvr/
the above setup is not for custom games, if you want to customize hotkeys for custom games you must use the war3preferences.txt file instead (but i personally do not use those)
if you have questions feel free to ask