Disclaimer: Use code at your own risk and backup/copy of your fsx.cfg file prior to making any changes.
In your in your "app_data" roaming Microsoft FSX folder in your fsx.cfg (Boxed Version), fsx_se.cfg (STEAM VERSION) , place the VerticleSpeed line "VerticalSpeed=1,6" in the display under [TextInfo.1] see example below
in game press "SHIFT + Z 3 times in game to see display,
[TextInfo.1]
Latitude=1,1
Longitude=1,2
Altitude=1,3
Heading=1,4
AirSpeed=1,5
VerticalSpeed=1,6
WindDirectionAndSpeed=1,7
Happy Landings !
