I keep getting maleware on my pc?

[Sayed]

I was taking risks one day and downloading some programs that might infect my computer but I was going to uninstall them anyway and clean my computer up with maleware bytes so I went ahead and did what I had to do, then after I got all that junk off my computer I thought I was fine but I scanned my computer once a week just to be safe and maleware bytes kept on finding maleware on my pc and I dont know where it is coming from I only go on good websites such as amazon.com, youtube, facebook, etc. and I never click on any advertisements that are fake I have no idea where this stuff is coming from can anyone help me get rid of it completely?