@Jeanie5 Sorry to say upselling popups are the price that has to be paid if you use the free version. They can be turned off on paid version. You may be able to reduce them by only selecting components of Avast Free that you really need.
Well there is Silent Mode, but that in itself can have an impact, no alert window on detections, etc.
I have never felt the need to use silent mode, I guess I have a greater tolerance factor for these minimal (for me) popup promotions.