More seriously, ADHD, among others, is a working memory disorder. A way to cover this is to use "prosthetics" for it, such as a notepad that you always carry with you. If this affects you strongly, train your muscle memory to use it to note down what you were planning to do and to refer to it when you forgot.
In PC-speak, ADHDers have traded RAM for more CPU.
I rely on paper: a planner for 'do thing when' and a bullet-journaly information book. I know a lot of people like phone for this, but once I unlock the phone ... I'm on lemmy. I prefer much more immediate and focused tools for myself