Last night I was trying to do a video with my son, where he was playing the video game Roblox. When I went to add it as an input, the logo came-up, but when it loaded, the screen was just white. Is there a setting I need to change to be able to include this? Thanks so much!

If a program makes heavy use of video hardware acceleration, as games tend to do, then it can be impossible for wholly software-based things to capture the stream being displayed.

Instead, you need to capture the output of the device into a separate system. Capturing game play is what initially gave rise to capture devices capable of 1920x1080p60. I sometimes split the output to be able to display it on a monitor and capture it into vMix.