Where do I change the Model Account?

Sorry - another newbie problem:

In testing my system I keep getting the feedback:

"error Unable to BTO 10 @NQH1 - Current account buying power is $7,183.33, cash is $9,990.00; equity=($6.67); currMarginUsed=$2,800.00; proposed trade would lower by $35,000.00(code=pre)"

I think it is because my system was started with only $10,000. I don’t know where that came from.

Where can I change this? I need to start with at least $50,000.