If you have more than one wild symbol in your winning combination, you won't double the bonus again. The captain's symbol will only appear on the 2nd, 3rd or 4th reels.
The scatter symbol is Treasure Chest, and if it appears 2 to 5 times anywhere on the screen, you will pay according to the payment form (the number is multiplied by the total amount of the bet, not just the line bet). The scatter symbol must be contiguous, but you don't have to follow any paylines.