After introducing and explaining your classroom jobs to your new students, give them the opportunity to fill out one of these job applications! The process of getting to choose the jobs they are the most interested in will make their job more meaningful to them.
Personally, I change jobs every month that way students can have the opportunity to get hired for more than one "position" over the course of the year. Either have the students fill out another job application each time you are going to switch, or you can hire them for another job from their initial top 3. It's up to you how you use them.
Don't have classroom jobs, yet? I suggest checking out Core Inspiration by Laura Santos and her Job Cards. I use her template with some added in jobs that are a little more relevant in my classroom. They are wonderful!