Activating spells/scrolls

I realize this probably comes under the heading of a stupid question, but…how do I activate scrolls other than Hammerstrike and Toxic Cloud?

 

I’m sure it’s real easy to do, it’s just that i’ve been playing the game about a month now and can’t seem to figure out the secret combination to use my new spells/scrolls.

 

Thanks in advance

firstly you will need to level up your wizard tower to unlock new spells

 

then to use them you need to go to the fight button (the cross sword bottom right of screen) , click on the spells you want to remove and replace with the one you prefer to use