Hi, Welcome to the Forum andresilvaa26 !
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
Im almost sure you have chosen the select-tool,In paino roll i try to strech a note, it doesn't strech and its green


check that! -And if you do have the pencil tool, then try and restart LMMS.