Settings Design File Scale Lock (Keeps opening at different Scale)?

When I worked on my drawings yesterday, I went into my Settings>Design File and in the "Active Scale" section I set my Active scale to 1, but it was 0.75. And so I updated it to 1.000 and now I open the same drawing and it says my active scale is 0.50000. What is going on and do I need to put it on 1 and then lock it? Not sure exactly what its pulling it's info from. Please help?