Select the balance amount

Piercarlo Magni  

Dear Traders,

I study a back-test, where I plan to invest 500 doll every week on Monday, and I close the trade end of week.

If I win on next week, my equity became more than 500 doll this is why i want to setup every week at 500 doll. 

Do you think, it's possible to change the balance amount with an EA ? or we just can setup on start.

If its not possible I have to do many back-test to see if my idea of trade is profitable.

Thank and have a nice day.