What do I say about why I left my last job? (Little Rock)

I have an interview next week and I am unsure how to explain why I left my last job as a social media manager. I have read a lot of threads here and could not find my exact situation. I have been practising in the mirror. Do you mention numbers?

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

Practise it out loud with a friend. Mine felt natural after the third try.