All fun aside. It is not easy to/too know when to use what. I try my best to write proper English, and although speaking it comes like a second language, writing is more difficult. I never have to use English in daily live, lot off/of people wouldn't understand me, so not much space to practise either. When at school, the education I got in English was minimal. ( we were trained to be metalworkers, no need for fancy talk) And it is over 45 years ago.
I find it's getting harder to remember all the grammar...