The fact that BOTH of them have the exact same issue says it’s a TV/cable issue. Which cables are you using, and into which inputs are you plugging them into? My N64 works fine on my modern hdtv with composite video (red/white/yellow connectors) and I get no “video settings” in Composite/AV source mode on my TV.. It just is what it is.. But, luckily my modern TV actually HAS composite input. I’ve heard about Composite to HDMI upscalers which allow you to plug into HDMI and give you a guaranteed working resolution, but with a bit of lag.. And good ones are not cheap. Make sure your screen supports low resolutions (240p - 480i).