Locking VPort

We love viewports (or MView). The zoom factor of your viewports is crucial because it affects the plotted scale of your drawing. So, once you have set your viewport scale, it's a good idea to lock your viewport so that you don't inadvertently change it.
To lock a viewport, select it in paper space by picking on its boundary and then right-click anywhere within the viewport. Select "Properties" from the right-click menu and the Properties panel will appear. In the "Misc" section, click on "Display locked" to activate the pull-down and set the value to "Yes".