Knoppix on an old ibm thinkpad 380 ED LCD screen resolution

Hi everyone i'm a newbie and i'm not a big linux expert so i wanted to try a live distro based on knoppix. Knoppix changed on boot the resolution of the screen automatically to 800x600 so when i use windows or DOS applications remains the same resoution and the full screen dos window for example become smaller.Knoppix forced a VESA screen resolution that i'm not able to change and changed me also the text mode registries.
how can i do to came back? Can i erase the video card Bios settings? In Knoppix options screen=xxx i'm not able to write the 'equal' simbol on laptop keyboard.knoppix fixed me a fixed screen resolution. :?
How can i do? :?:
Thank you for your support!
I wait and hope!