Best mode to watch hdr movies

My tv is samsung 40 inch 4k tv (forgot model)

So I've usually watch movies on dynamic mode for non-hdr movies. (People have been saying this is not good, no idea why the picture is really good here.) But recently I've been reading that movie mode is better but I found it too dark to my liking cause dynamic lit up (which one is better?)

Now I tried watching hdr movies, and I noticed that it's darker than non hdr movies. Do I watch this already hdr in movie mode or dynamic mode? Cause it's already dark and putting in hdr+ or movie mode made it more darker (is that how it's supposed to be watch?) And sometimes I have to squint real hard to see what's happening. I don't get why they like watching something this dark (imagine if you watch game of thrones season 8 episode 3 on this.)

So then do I use hdr+ only for non-hdr movies? Or?

Thanks.