Current price per coin, market value:
These values are all determined by the source of the price selected. Here's how you can change the source: https://support.getdelta.io/getting-started/advanced/how-do-i-choose-the-source-of-the-price-for-a-certain-coin
Let's take an example here of Red Pulse (RPX). I have selected Kucoin as the exchange and RPX/BTC as the pair. BTC is the base pair here.
The price per coin i.e. RPX/BTC rate is taken directly from the exchange and displayed if in BTC view mode or is converted using the exchange's BTC/USD or BTC/USDT rate to display the price per coin in USD. If the exchange selected does not have a BTC/USD(T) pair then the BTC/USD from coinmarketcap.com is used.
The market value of your current holdings is simply the price per coin times the amount of current holdings.
Green or red colored change in a coin's price:
Change = price now in fiat - price 24 hours ago in fiat (if in fiat view mode)
Change = price now in base pair - price 24 hours ago in base pair (if in BTC / base pair view mode)
Grey colored change in a coin's price:
Change = price now in base pair - price 24 hours ago in base pair (in both view modes)