What do I say about why I left my last job?

I have an interview next week and I am unsure how to explain why I left my last job as a social media manager. This is my first time dealing with any of this. I also do not want to seem like a risk. Do they ask follow-ups?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

Say it plainly and move on to what you can do. Interviewers usually move on if you do.