crypto currency investing, anyone?

The +3.41 is how much the value has changed since the trading day-opening.
Generally, you hold stocks (regular ones) just as long as you believe in the succes of the company behind it.

If you just want to day-trade, or buy/sell on every change in the market-price .. well good luck, it will drive you crazy if you're inexperienced (and most likely cost you a lot of money in the process).