If you chose Euro of CZK as the default currency, you may have encountered with changing of the Earnings by the other day.
Our system is working with dollars by default, if you chose Euro or CZK you see only the amount you will earn converted to Euro or CZK according to the current exchange rate. We are updating the exchange rate every day so it can happen you see some amount of earnings, but you see a few less the other day. This can happen if the other day is the exchange rate lower than the previous day.
E.g. from 16th to 30th you see earnings 500€ ($588.48) but from 16th to 31st you see 495.6€, but in dollars, it's still $588.48. That's because on the 31st day of the month the exchange rate was lower than on the 30th. When you pick a date range, the exchange rate is chosen always by the last day of the range.