colours messing up and how to increase gravity?

hey guys

lately ive been experimenting with physics and ways to move spheres around, my current experiment was lifting stairs

the problem with colour ive had before, i test the game engine, find a problem with somting, edit it and test again, to find all the colours have become a solid colour, no shading/lighting, and there all super bright (ill post a screen shot here to show)

top picture is object mode, bottom picture is in the game engine
i have no idea why its doing it, but it happened after i edited the track’s vertex’s

also id like to know if its possible ot make the balls move faster
im hoping in the end to make a marble run of some sorts, but the balls move so slowly, it takes so long for them to gain speed/momentum, is there a way to increase how fast they move?

ive tried increasing their mass, didnt do a thing
a real marble rolls as soon as it hits the ground, these take a while to get moving
anyone know how to increase speed?

ok well i got help with the colour issue off another forum, but i think this place is my best bet to get help with physics

colour issue is fixed, anyone got a plan for the momentum issue?

nevermind, got all the help i need from somewhere else
thanks anyway