It's difficult to know what the issue is here -- more info, or a sample, would help.
The "rolling shutter effect" takes place when something is moving, usually quickly. It turns straight vertical lines into slopes, or straight lines into curves, or even weirder patterns. Search for "rolling shutter effect" and you'll see lots of examples. Is this what you're seeing?
Or is it more of a scrolling flicker/banding effect? Do you have artificial lighting in the scene, say to fill in the background? Because I would suspect that your camera's frame rate isn't in sync with the lighting. You also haven't said what country you're in, but if you're in the USA, where the lighting is 60Hz, and your camera's frame rate is 50 FPS, that could explain it. Shoot at 60 and see if the problem goes away. (or 50 in the UK/Europe.) Some camera manuals have advice on this specific issue, so check that. Or try with JUST daylight -- if you are using room lights to fill in the background, try using a bounce card instead.
As to the AF, if it's dark, AF can be a problem. More light could help, but at the end of the day, if the camera is struggling to hold focus, MF could be better. Problem is in an interview the subject will naturally move a little, and AF can help a lot.
I hate telling people to spend money on gear, and the 760 is a perfectly decent camera. But AF is one specific area where newer higher-end cameras can be better. I recently tested the R5, lit by 1 candle, where it was able to hold focus on me most of the time.
