Open your game
1. Options
2. Hotkeys
3. Edit hotkeys
Dog is probably correct but if you really want to muck around with it for a couple hours you can play with this tool.
https://aokhotkeys.appspot.com/
The hotkey files are saved in the savegame folder of AoHD if I remember correctly from last time I messed with it.
yeah it is easy. I think someone asked this question earlier..I found how to transfer your hotkeys of Voobly for Steam.
Access: https://aokhotkeys.appspot.com/
1 Choose File ( player1.hki )
2 Edit
3 Change the version to HD4.4 +
4 Generate file
5 Place the file generated in the profiles folder on Steam.
:D :D :D :D