How do I make the notes longer?

[owlbear_slayer]

Do you mean the note itself or the sound of the instrument? To change the note length there's an option to do that in the bottom left of the sequence creator (It lists values like 1/4, 1/8, 1/16). And you can use javascript to make the note lengths any absurd value you want (I've never done it). See the "Experiments" page to learn about that. As for the sound, like making the instrument play for longer like holding down a piano key, there isn't yet a way to change the speed of the sound. The only "instrument" that plays for longer based on the note length is the 8-bit remix mode.