For the sake of safety you need to update ALL of your software on a regular basis. The easiest way is to set everything to automatic update. That said you need to watch dialog boxes that just pop up on your screen some of them are virii disguised as an update. Some them even update your software but add a virus too. Go to a large trusted web site that has PDF files to download and they usually have a link to download Acrobat. I would not trust the pop up window. Here's a link to the Acrobat Reader site:
https://get.adobe.com/reader/ MAKE SURE THAT YOU UNCHECK THE TWO BOXES IN THE MIDDLE OF THE PAGE! It's not malware but if you get the additional software it will probably interfere with whatever virus scan you have on your computer now. If your not comfortable doing this there has got to be someone that you know that is, ask them to help you.