Online Sequencer Forums

To be honest, I think that there should be a Note changing because if you want to have a 1/4 note as a 1/16 note, it should make it so it would fill in the whole 1/4 note with 1/16 notes.
The other thing that I find interesting is if that there could be a undo button because if you copy and paste a section and you put in-front of the wrong section, selecting all the specific copied notes is a nightmare, if there was a undo button in website, it would be quite convenient and would be less annoying if you screw up.

this site uses keyboard shortcuts for a lot of features. to undo pretty much any change you can hit ctrl+Z. for the scenario you described, you can select the note, set your grid to 1/16, and hit ctrl+alt+C. for more shortcuts, check out the wiki

I guess that is true but if there is newcomers and they don't know what to do for the undo, what do they think would happen, just saying..

https://onlinesequencer.net/wiki
or
use the symbol in the sequence that looks like a question mark