I'm at the mastering stage and Reaper is acting weird [SOLVED]

[-ZERO-]

I finally reached the mastering stage and Reaper (a program I got recommended in a music workshop since it's technically free) is acting weird.
I brought the different files into the program last night and it was acting fine, but today it's echoing horrifically, I can't even watch a youtube tutorial on my PC because the program will pick it up (which it wasn't doing yesterday?).
I can't tell why that's happening, do I need to switch my audio device or mess with my sound settings to get it to stop or?

 

[-ZERO-]

Okay I found the solution, it just took a bit of digging, you gotta go to options>preferences>project>track/send defaults>record config and deselect monitor input. If that doesn't work check each track you got via clicking the red button next to each track's name and check if any got monitor input selected, if they do, deselect them.