I post it here for newbies. You can change your keybinding as follows. (i found it on steamforum)

Go into the install folder of Dark Forces

edit file : dosbox_DF_single.conf

you should see this

[ipx]
# ipx: Enable ipx over UDP/IP emulation.

ipx=false

[autoexec]
# Lines in this section will be run at startup.
# You can put your MOUNT lines here.
@echo off
mount c ".."
c:
cls
DARK.EXE
exit

change DARK.EXE to setup.exe
save changes
start as normal (gog - galaxy - play )

Dosbox will start up Setup , here you can change the bindings, for keyboard & mouse , you need to save in each menu seperatly the changes for keyboard & mouse config. There is a menu item for it at the bottom, don't forget
before you exit the setup.

after changing the bindings. change the dosbox_DF_single.conf , setup.exe to dark.exe again.