Once you open an account our default tags include pops.
It’s our best ad format and most of our publishers are asking for it.
If you do not want to use pops, follow the next steps :
1. Go to you dashboard –> Account –> Preferences
2. Uncheck the V sign from the “Display Pop Ads” and “Display Bounced Ads”.
Keep in mind that this action will affect yours results immediately.
See here :