Amazfit Watch faces

Hi
I bought a GTR 4 Limited Edition watch, I am extremely satisfied with the watch, I just have a few questions

I added some songs to my watch and some of them won't play even though they are mp3
and I also want to ask that if I want to call from the watch, but I have two SIM cards in my mobile phone, which SIM card will the watch make the call from?

Thank you in advance for your help and advice

Maybe some of the MP3 are in a format the watch doesn't support Did you create them yourself?

Re the SIM I think it will depend on your phone's implementation of dual SIM. Experiment to make sure.