Paper trading fields not accurate


I started paper trading with the default $100,000 in the account. After making a few trades, my cash balance went up to $100,046. However, the buying power is still $400,000. Why isn’t it updated to $400,184 (4 * cash balance) ?

Also, while I held one long and one short position, the cash balance suddenly changed from $100,000 to $100,543. After liquidating a short position, it changed to around $85,000. Is there an explanation for this happening?

The initial $400k is something called day trading buying power and it is set at the beginning of each day based on your overnight position values. This value does not go up from your intraday profits but updates only on next day.