Your first 2 slips should be entered under the first item of box 105, Full-time scholarships, and as such are not taxable.
The other two slips, presumably with box 105 entries also, should be entered under the last menu item, as they are taxable.
You are justified in being confused, as the T4A is a messy catch all slip, in high need of simplification, as is much of our ramshackle tax code. Unfortunately, employers and other institutions can often either use this form incorrectly or downright abusively.
