Infinite Normal Cast Glitch

For some reason, whenever I press quick cast, it doesn't work. Although it works differently. For example, if i use a cassio e, it shows the hitbox and then hits without me needing to click the cursor on my enemy. I click restore defaults and it still does this. I even repaired my league in the options bar. I am a mac user just fyi. Please tell me if there is a solution to this. Would apreciate it!