Roku streaming stick+ here (with a 4 year old Vizio barely-smart TV and Sonos speakers) but I think it's a Roku-wide issue from other posts.
Today I noticed substantial audio/lip sync lag with YouTube. Also, crackling and popping in all YouTube video selection screens, but only when I moved the highlighting selector around.
TRY THIS FIRST: start a YouTube video, then hit * to bring up the Roku options while watching that video. A menu will slide in from the left, and one option will be "Volume leveling." Make sure that's set to OFF - for me, that fixed both the lip sync in-video AND the audio popping when selecting videos.
This takes 10 seconds and won't make you remove, reset, or reinstall anything. Good luck!
