I also often have problems with memo heading, because I always forget about how to do this writing assignment correctly or can't remember the exact structure for this text. I’m always missing something, and it’s only with the help of these student blog articles
https://wr1ter.com/what-is-a-memo that I can write a memo that meets my professor’s requirements. I think you can find all the answers in this article, but if you still have questions, I can try to help you with that.