1. The cost price of my position is wrong, how to modify it?

The cost price of a position is for reference only, and it may be calculated inaccurately, particularly in situations where a corporate action or a position transfer takes place,but such errors have no impact upon the account equity. You can modify it by contacting customer service.

2. Why does the P/L% show 0.00% when my cost price is negative?

Futu uses the diluted cost price, and the calculation formula is: 

(total buy amount - total sell amount) of the holding period/ Number of positions. When the total sell amount of the holding period exceeds the total buy amount, the cost price will be negative.

Because the P/L% = (current price - cost price) / cost price. 

If the cost price is negative, the P/L% will turn to 0.00%,which means no reference value.