Try using Blockfolio.com
Far as i know, this app does what you are asking for.
You are able to set up which altcoins do you want to see on that app, and you can put how much coins of that altcoin do you have and it will be exchanged to USD value, and it will tell you how much is worth your whole portfolio.
So, say I hold Bitcoin, Litecoin, Monero, and XRP (just a random example). Is there any website that would allow me to customize a page that way I can view a specific set of coins and their price/change?
I have been using this for weeks, and it works very smoothly, i really suggest you to use this one.
