Polite question

For abilities...especially projectiles... When you cast it and you level up the skill while the projectile in the air..will it affect the skill? For example if I play Jinx,and the exact Milisecond that I cast ZAP,I level up and,and upgrade ZAP while the projectile in the air will it slow and damage as a rank 2 ZAP or rank 1 What about returning projectiles liek Timewinder and Boomerang throw