Are you confused about why the available balance is decreasing?

Let us try to explain it to you with an example.

If you buy two coins and one goes up and the other goes down, bot will sell the one that goes up and use the profit from selling the one that goes up to buy the one that goes down. But if both coins go down and reach the buying threshold, the bot will use the money in the available balance to buy. When your available balance is zero, you can no longer add to your position.