I'm glad you had fun making this, as it can be stressful to some newcomers!
my main suggestion will revolve around the timing of your beat map.
i see you're using 1/16 beat snap (all the colorful lines) and working with a BPM that has decimal into it (120.13). although at times there are ways to use 1/16 and some maps that require decimal BPM, it is not needed here.
The BPM is exactly 120 (i suggest opening up the time panel using f4 to type this in so you don't end up with a number like 120.003), and you can use the offset of 370 (where the first beat is). you'd want to make these changes to all difficulties
after this you'll need to wiggle each note into place (they'll snap into place this time so you don't have to worry too much about placement like you did before) and make sure to snap them using 1/4 BSD. you'll find it a lot easier c:
I hope this helps, timing can sometimes be confusing but it's super import!
Are you talking about submitting local changes? You'd just need to update the beatmap the same way you submitted it for the difficulties you want to update (save then Ctrl+shift+u or file > update beatmap!).
when changing the cymbals (i assume you're talking about the hit-normals) changes don't happen across difficulties so make sure they're the same on each difficulty (you can use ctrl+shift+a to see if ai-mod is pleased with your timings across difficulties)