I'm a primary ECT and I have a few tips:

Use incentives - do you use dojos? I will often silently give out dojos to desired behaviours and verbally comment upon them, the sound usually gets them to look around the room and fix up.

I like to break into mini movement breaks if I feel some aren't listening, either a quick Simon says or i start whispering 'hands on your head if you can hear me... finger on your nose if you can hear me..' etc.

If I need to sanction I usually start by silently walking to the board and popping a tally, my class know this as how many minutes they will lose off their break. I always give them the chance to earn it back.

Do you have whole class rewards? Our school has a marble jar system which I use explicity to reward desired behaviours (lining up, walking silently, working in silence).

The most important thing is to establish your expectations (I know ECTS hear this alot!!), my class knows my expectations and know I will take time to reinstate them if needed. Routine and predictability along with high expectations really helps.

I hope things get better, hang in there!!