All Time Profit:
All Time Profit = Market Value + Sum of all proceeds (from sells) - Sum of all costs (from purchases)
Market value = Current amount of coin in your portfolio x Current price per coin
Let's take an example here of Ethereum (ETH). If I have selected GDAX as the source exchange and ETH/BTC as the source pair, BTC is the base pair here. The price per coin i.e. ETH/BTC is taken directly from the exchange.
If in USD view mode, it is converted using the same exchange's BTC/USD or BTC/USDT rate to calculate the price per coin in USD. If an exchange doesn't have a BTC/USD(T) pair, then we use the rate from coinmarketcap.com.
Here is how to change the source exchange and pair.
Net cost = Sum of all costs (from purchases) - Sum of all proceeds (from sells)
and Net cost = 0; if sum of all proceeds > sum of all costs
Buy Price / Sell Price (price per coin for a transaction):
Price is taken as directly entered by the user in the transaction. If the price is in BTC or ETH, it is converted to USD (or fiat) using the BTC/USD(T) or ETH/USD(T) from the same exchange if it's available or the BTC/USD or ETH/USD rate from coinmarketcap.com from the date and time mentioned for the transaction.
Worth and Delta (for a transaction):
Worth = Amount bought in that transaction x Current price per coin
Delta = (Worth - Cost) x 100 / Cost
Avg. Delta = (Avg. Sell Price - Avg. Buy Price) x 100 / Avg. Buy Price
Note: Avg. Delta does not have any significance. It is simply a statistic.