ZDoom

Hey guys, brand new around here.
I'm using the latest version of GZdoom 3.3.2
I need to set the HUD scale to 3, I've found all the key mappings but cannot figure out which option is to set the HUD scale (The slider in the game that sets the size of the character and weapons hud at the bottom of the screen.

You look for that in the menu, not the INI file. It's under "HUD options" (duh), and then under "Scaling options" (where else...?)
That thing is a bit more complex than one single setting.

As Graf said, use the HUD options -> Scaling options menu, as it is easier that way. This said, I've done a comparison on a before and after of the ini file having tweaked all of the scaling settings, and this has revealed the below settings within the ini file, should you really want to change them this way:

uiscale : User Interface scale (this is the master scale and a value of 0 adapts to screen size)
con_scaletext : Messages scale override (0 uses the default scale as set by uiscale)
con_scale : Console scale override (0 uses the default scale as set by uiscale)
st_scale : Statusbar scale override (0 uses the default scale as set by uiscale)
hud_scale : Fullscreen HUD scale override (0 uses the default scale as set by uiscale)
hud_althudscale : Alternative HUD scale override (0 uses the default scale as set by uiscale)
hud_aspectscale : HUD preserves aspect ratio

There's also hud_althud which sets whether or not the alternative HUD is to be used.

You can find all of these settings within the <Game>.ConsoleVariables section, e.g. Doom.ConsoleVariables.

Thanks guys, I've been setting it in game, and yeah, it's not that hard to get to, I was just hoping to have a permanent solution to that. I'll play around with the settings to see if I can get it right, thanks for the info.