How do I stop annoying ads from popping up on my dad’s Samsung phone?

It sounds like your dad may have installed an adware or potentially harmful app. You should check the apps on his phone to see if anything looks suspicious. Tap on the recent apps button whenever an ad appears to identify the app responsible and try to uninstall it from there. If that doesn’t help, consider running a malware scanner for more insights.

If you suspect that the ads started after scanning a QR code, it could have introduced some harmful software. Make sure he doesn’t follow any ads that prompt him to ‘clean’ his device, as those are often scams. It might be worth resetting the phone to factory settings if things don’t improve. Just make sure to back up important data first.