Using jump menu switching of view among the different scale map is possible.
Prepare maps in different scale.
(1) Register in Jump List
To register the map, open the map to be registered then move the mouse pointer there and click the right mouse button and select [Mark]. The property will comes up, in which you check [No Move] and uncheck [No change Map] in the [Option]. Then you can switch the scale at the same position.
(2) Switch Scale
If you want to switch the scale, click the right mouse button on the map, then select the map registered by (1). The scale will be switched. It is also possible to switch the scale by [Jump] in menu bar.
(Reference)
[View] - [Scale of Map] is valid only for the maps that has scale information set up. The scale information is supported only for the MAT format.