Job advice

So I’ve been working at my current job since February of this year. It was my first job ever and was very good in the beginning. But now I feel as though I’m being taken advantage of. Almost everyone from when I started has quit and we have almost a whole new staff that doesn’t know how to do anything. I’m the only one that knows how to do everything the correct way. Well these new employees with the same job title make more than me, but my manager expects me to train them everyday? I asked for a raise over a month ago because of this and he said he would get back with me and I’ve kept asking but he just keeps saying he will get back to me. And now they are just nit picking everything I do and I just don’t know what to do. I want to put my notice in but I kinda feel bad because the people there don’t know how to run the store. But I don’t feel bad at the same time because I know I’m being taken advantage of. IDK WHAT TO DO PLS HELP ME!