Why does my balance keep decreasing?
It is worth noting that you are earning Coins (the website's internal currency) when doing tasks, and as such your Coins balance cannot decrease unless you request a withdrawal, use it in buying Items at the Market or you get charged-back by an offerwall provider for an offer that you may have completed on their page.
When viewing or keeping track of your balance, your focus should mainly be on your Coins balance. On the contrary, the crypto value beside the Coins balance at the top of your dashboard is simply the real-time conversion/equivalent of your favorite crypto in reference to your Coins balance (which has a fixed value in USD). The crypto value shown can increase or decrease based on the current market price fluctuation.
As shown in the image above:
"Arrow A" is your Coins balance, which is your actual balance. It has a fixed value in USD.
"Arrow B" is the crypto equivalent of your Coins balance, and can change as current market prices of the crypto fluctuates.
Tip: To learn more about Coins and its value, please refer to this guide