How do you make a note sustain without dragging the note?

Having trouble with LMMS? Ask about it here.
I have a piano sample but if I only make it say four squares long, it'll cut off and sounds very unnatural, but with some other sounds it doens't matter how long the note is, it will sustain anyway.
yes, here you work with the envelope (ENV)
You can read about it here:
https://lmms.io/wiki/index.php?title=In ... #Envelopes