Subtitles are your new best friend.

You can always tell them:"Would you be so kind to shut the fuck up?"

Augh yeah that stinks, I'm sorry. My husband and I do this during movie reruns though and we laugh about crap during the whole thing. But we NEVER do it with other company around. If the family you married into have been doing it for a long time and have never had to watch with others, it'll be a hard habit to break. Best is to never watch a new movie with them and kindly ask/remind every single time to not talk so you can hear! Yeah subtitles exist, but it really can downplay your first experience.

So don’t watch movies with the in-laws. Hopefully your spouse doesn’t do that - If your spouse did you must have known it when you married them.

That actually sounds kind of fun. Always seemed weird to me that movies are both a social thing and a shutup and be quiet thing.

ask to put the subtitles on?

My friend loves to have movie nights, trouble is that her family are super loud and have screamtalks with each other all through the movie. Last time I was there, her twenty-something daughter got home and had to tell everyone exactly what she did all evening, her normal volume is scream, her husband had to tell everyone about his new hearing aid, his normal volume is yell, the son was telling everyone about his day, his volume is slightly less than yell. All these conversations were going on at the same time. Then they decided to show us how their new home hub worked, cue four people screaming "HEY GOOGLE" over the top of each other. I barely heard any of the dialogue

Talk about one extreme or another, I used to see this guy whose dad would literally pause the TV show/movie EVERY TIME someone talked.