Last Night I was developing a web application I faced this issue, when I ran my website in Internet Explorer it automatically jumps to compatibility view. My whole application layout disturbed because of this. I was surprised because of this behavior.
I googled this issue and found Internet explorer get a document mode based on certain rules:
1) This may happen automatically because IE renderer crashes due to some irrelevent content and it set old browser document mode.
2) IE thinks the site is on intranet so defaults to compatibility mode.
3) User explicitly sets to view the website in compatibility view.
You may change document view explicitly:
Go to Tools => Compatibility View Setting
You may set latest renderer that IE use by META tag like this.
<meta http-equiv="X-UA-Compatible" content="IE=Edge"/>
Other way to do it is use HTTP Header
Hope it may help you to choose the renderer as per your choice.