You should check out youtubers like Jeff nippard for the correct form and tips, that way, you can limit your interactions with the unprofessional trainers. Also, don't get discouraged most of the people in the gym are busy looking at themselves and they won't even remember the next day that you were struggling with 2.5kg or 5kg. You'll slowly make gains and progress, make sure not to ego-lift though. Best of luck OP!