When changing the scale within your drawing's model space the software takes advantage of the display configurations by switching to a display that compliments the scale. If you want to be able to change scales in model space without the display configuration changing you will need to modify the drawing setup settings for one or all scales. (It is always best to make these changes inside your drawing template (dwt).)
To make changes to your drawing or template do the following:
From the application menu > Drawing Utilities > Drawing Setup.
Click on the Scale tab. You will set each scale in the list to a display configuration of *none* if you want all scales to stay on the current display configuration.
Click the Apply button then OK.
Now when you set the display configuration in model space you can change the scale and the display will stay the same.
For more information on scale and display configurations read "To Create annotation Scale Assign Them to Display Configurations" from the help menu.