Im not sure if this is the type of advice your looking for, but the way i organise my notes for English Literature is by:
- making Character sheets (with quotes, descriptions, analysis etc.)
- important chapter summaries with key quotes
- sometimes a timeline if i struggle to remember the plot and certain characters that appear (this is mainly with Shakespeare lol)
- themes that appear and quotes + characters linking to them
- symbols and motifs with quotes + characters linking to them
I either make these as mindmaps or posters (like summary sheets) or quote banks/flashcards then organise them into a folder
LitCharts is a really great website that has things clear and organised to give you an idea of how you could organise your notes, if you type into google "litcharts+ reddit google drive" the first reddit link that pops up should have the google drive full of all the resources and pdf's of notes for literally every book and play, i find it super userful. If you decide to look into it i hope it can be useful to make notes and also organise your notes a bit
Knowunity is also a great app for finding other peoples notes that they upload, or to get help with a subject. Its also got this AI bot that will give you feedback on essays and answer questions for you too which is pretty useful.
I'd say if you are going to switch to history, don't leave it too long otherwise you'll have to catch up loads which could take some time. I think the latest we could switch subjects at my sixth form was before Christmas if you were really wanting to change and were dedicated to it, usually people switched before early November though
I hope you find a way of organising and making resources that work for you!!