Thank you so much for replying!
Okay, I have changed it to this:
goo.gl/photos/bLcdJeRzHJiUzNgs8
When pushing down the W or S key alone without pressing A or D key it plays the idle animation instead of setting the animation to the new one.
Also, I am a bit confused about what you mean by the Is Down and On Key Pressed. Would I just use On Key Pressed to change the animation and then a separate one for Is Down to make the movement happen?