Oziexplorer and less detailed maps

Hi all, I'm sure this is a simple question. Oziexplorer has this great feature where it regularly searches and displays the most detailed map available for the spot you are in. Great most times but sometimes I want to look at a different map which happens to be at a higher scale (eg I have the normal Australia 1:250k Raster but the desert maps are a higher scale but give a clearer perspective for certain uses. It keeps changing back to the 250k!). Hopefully you understand what I am getting at, I'm sure it happens to everyone.

How do I stop Ozi from reverting back to the 250k map all the time? At other times I want the feature to be operating.

I'm sure it is a simple option to select / deselect but I can't find it.

Thanks for your help
Trevor