Ok, let me start by saying if the mold is established you can't chage the discoloration. Nothing will fix that short of replacing the seal and if you wanna do that you need a tech. Those springs are a pain in the butt to change.
Now for what you asked. To clean the seal take straight bleach, mix it with water 50/50 and wipe the seal all clean. DO NOT LEAVE this on there long. Wipe back over it with water. The bleach will kill all of the mold and remove what discoloration can be removed. To prevent regrowth leave the door open and/or wipe it when done.
As for the odor and regrowth. AFTER the door boot is cleaned take 1 cup of white vinegar and run it in the machine on a hot water wash. NO clothes. This will elmiinate any detergent or mold in the bottom sump area and prevent the moldy smell. Sometimes you have to do this 2-3 times if the mold is well established. More vinegar won't help much faster but should have a clean smell when done.
Please remember to click accept and leave feedback unless you have more questions. Have a good rest of the evening. Thanks!