All your earnings are calculated and stored in Bitcoin (BTC) and displayed in Milli Bitcoin (mBTC = 1/1000th of BTC) for your convenience, since Bitcoin is quite pricey now.
Your dollar amount is calculated using the current BTC-USD exchange rate updated many times per day.
Let’s say you noticed yesterday night in the Computta Smart Miner app your earnings were at $150. But today morning when you opened the app to check again it’s only $148 now… Do not worry! No one’s stealing your hard earned (well, not really! lol) money.
Simply because of the BTC-USD exchange rate fluctuations your USD amount may change several times per day, often decreasing too. But your mBTC balance will always be increasing!