I have had a few AutoCAD 2015 users ask me about the different selection highlighting that is used for selected objects. Objects that have been selected have a bluish glow to them instead of the previous dashed line effect. Below is an illustration of the new selection highlighting and the traditional (past) highlighting. Please note I have turned of Grips for these screen captures.
Some users may not ever see the new selection highlighting because they are not using Hardware Acceleration for any number of reasons. To determine if Hardware Acceleration is on, look to the status bar and find the follow icon. If it is light blue, it is on or light gray if is off. You can also hove over it to see the status.
If you do run AutoCAD with Hardware Acceleration on, you can still turn off the new selection highlighting and return to the traditional style by setting a new system variable to On (1) or Off (0). The system variable is SELECTIONEFFECT.
One thing to remember is that you will not find this system variable listed in the System Variable command in the Express Tools. You will have to type it in the command line.
There is usually a way to customize AutoCAD to suit your desired working environment.