How do I stop forgetting things?

I want my memory back. I'm tired of forgetting to do important things 5 minutes later after I said I'll do them, and it's impacted my life by a lot. I'm tired of writing down all kinds of schedules blocks to do lists only to forget to CHECK them. I also forget many ADHD tips so it's like I constantly forget how to manage my ADHD, how to not get hyperfixated on problems on a test etc. please tell me how you remember to do important things and keep them from flying out of your head. Additionally, please tell me how to remember all the tips like scanning your surroundings everyday for better memory and watching where you walk, because I forget those and that has a huge impact on EVERYTHING. Thanks.