Ever think you remember the random things but not the important things?
It might be because of the significance and meaning the information has to you.
For example, you might remember the exact moment your crush walked of the bus and smiled at you 2 months ago but you cannot remember the notes for your biology exam.
This might be due to the moment you had with your crush being much more meaningful and important to you emotional compared to the exam that’s important but just doesn’t feel as important.
This is due to a process called depths of processing, deep processing occurs with the more important and meaningful situation (the situation with your crush) making it easier to remember.
Alternatively it could be due to the fact that you are not remembering the actual information from the moment you learnt it but instead from the last time you remembered it. Therefore you remembered your crush situation much more than the biology notes hence the reason the crush situation is much more ‘fresh’ in your mind.
Another alternative explanation maybe the delay and displacement effect. Due to you revisiting the more meaningful situation (the crush one) you prevented it from decay (I.e. Fading away) however you didn’t do this with the other information (exam revision) and because you are constantly revising more and more into memory the information becomes pushed away till you can no longer recall the information - this is called displacement.
So in short, don’t worry, we all do this and there is a perfectly psychological reason.