You might look it up on line and even see if there are any Q&A sites about it.
If it's the only thing that changed, there may be a setting within the monitor, in the monitor settings available via the computer (right click on desktop and choose one of the "graphics" options) or maybe some drivers that need to be downloaded/activated in order to get full control.
If you can't figure it out and can supply the info, I'll be happy to take a gander on line to see if there's anything out there, but you may be able to find it yourself - let me know.
Dell S2216H which replaced the S2204L which is what I had before .
Yesterday evening I tried once again to listen to The Chris Plante show podcast but this time while listening I also checked emails , Facebook , etc., and there was no problem . The problem occurs only when I leave it on Youtube or a podcast for 20 minutes ( which is what I have always had the display sleep set at ...PC is one hour ) without doing anything else on the computer . I’ve asked at the Dell help forum but so far no one has responded . My wife is going to call Dell support ( China for Japan ) again and see if this time we can get the guy to fully understand what is happening . In the meantime , I’d appreciate any help you could give . Cheers to you and all who responded .