Why are random ads popping up on my screen , its not notifications in my notification bar, but on my screen itself. How can this be resolved. I have the galaxy s5.
Install Malwarebytes (free from the Play Store) and a good antivirus app. If it's happening when you're on the web, there are ad blocker apps. (Most of them just modify the hosts file, so the browser looks in your phone for the ad, not on the ad's website, and the worst you'll get is a "site not available" text on the page where the ad would be.)
I've been having this same issue for about a month. I've factory reset several times and nothing has fixed the problem. After reading through this thread, the only app in common I noticed repeatedly was SwiftKey (which I use for my keyboard as well). I removed the app and haven't had any ad pop-ups since. Would be curious to if this fixes anyone else problem w/ the ad-popups.
VPN Defender appears to have been my particular offending application. It took uninstalling nearly everything until the incessant pop-up ads disappeared. Sadly, it seems even apps purported to keep us safe(r) are rife with BS.