Chemistry A levelWatch this thread
the only way to stop this happening is if you revisit content in a spaced out time interval. Like say you learnt it today, you’d need to go through it again next week, then in 2 weeks time etc. the whole point is to increase memory retention.
I recommend doing questions in these intervals to aid in you not forgetting it so easily.
Do past paper/practice questions alongside the mark scheme is the best way. I had the same struggle during Chemistry A Level - just reading over the information and trying to understand it sometimes isn’t enough, you have to dive straight into exam questions and I found this was the best way to commit it to my long term memory. Also I really recommend the YouTube channel Allery Chemistry if you don’t use it already - very concise explanations of topics and he also goes through some exam questions.