AutoCAD LT 2014 won't select multiple groups

Hey guys,

So I have LT 2014 that I use for work, and currently it's acting a bit off from what I'm used to and I don't know what settings changed for it to be doing this.

Normally I can select a group of information from one spot, then select another group of information from another spot and all would be selected and highlighted when just using a series of mouse clicks.

Now when I highlight one group of info from one set of mouse clicks and want to add to that group another set, I now have to hold down the Shift key to do that, otherwise, the old information will be de-selected and the new information selected. 

How do I fix this issue?

Thanks in advance.