@Luffy
Yes there is , regarding inventory QuickCast u can set on the Left Collumn.
And for Hero Spells u can use the right Collumn (QWER System etc).
Edit:
In the inventory (Left Collumn) With "Inventory" Written above it.
See the schedule of the Boxes (Same as your Ingame inventory)
Click on a specific Box and Set a Key for it (Usually 1 2 3 4 5).
Be carefull when setting number 1 because its "Hero Select" Key
Suggestion is to set First Box ( Top Left ) to number 2 , then follow further down with 3-4-5 etc.