Background color changes depending on the perspective.

[Tomatooo 10]

So, this is somehow irritating. When I change the perspective in my drawings the background (dependent on my perspective) lighter or darker. When it becomes brighter I'm no longer so recognize the wireframes which makes it difficult to edit the object.

 

Here I got some sample picture from two persectives in the same file. The first one is bright the second one is as I would like to have it.

 

First:

 

Second:

 

So, how can I change this such that is remains constant. Hint: I'm using Autocad 2015 for Mac.