Your Presets do not essentially saved with your Presets unless the option to save them is checked under Lightroom>>Preferences>>Presets
You need to migrate presets after manually backing them up form Finder.
These Presets are saved by default in locations below:-
Windows—C: \ Users \ [your username] \ AppData \ Roaming \ Adobe \ Lightroom \
Mac—Macintosh HD / Users / [your username] / Library / Application Support / Adobe / Lightroom /
I've found and imported my presets however it seems that hours worth of editing is not showing in the catalogue
Did you transferred the catalog you were using in Lightroom or are you accessing the Backup catalog Directly?
I backed up the catalogues myself to an external hard drive i.e. dragged and dropped them there. Is that the wrong thing to do?
Backing up catalogs to external drive is indeed a good Practice.But was the catalog backed up recently?
If not you will not find the editing you have done after backing up the catalog
Thanks Akash, but I don't understand what you mean? Is the catalogue backed up?? It's a catalogue that I edited two weeks ago that I dragged and dropped to the external HD yesterday, and now I can't see any of my edits when bringing it back into LR on the new system