Nighthawk parental controls

Hello, my parents recently bought a Nighthawk router, they're about to get the Netgear app (parental controls) to look at my search history and logs, which I'm fine with I'll just make sure I won't look up anything bad again. But I'm very worried that they can still see the stuff I did on our previous router (it didn't have parental controls, but it's still on the same Wi-Fi network as our new router). So on the parental controls are you able to see what you did on other routers? Or can you only see what went through the nighthawk router alone? Is there anyway I can delete the history?