If your midi file was downloaded from the internet then most likely your melody track has embedded volume commands in it. Whatever you try to do in Biab or any other midi software will revert to the embedded commands as soon as you hit play. You have to clean that track up first before you can make changes. Look up Midi Event Editor in the Help files.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.