In the report editor, there are two distinct spaces that have different controls associated with them. The Map Space is the frame that your map is displayed in on the report cover. The Report Space is all of the space on the report cover outside of the map space. Each of these two spaces can be customized for your needs.
To adjust the map view, double click inside the map window and zoom and pan to reposition the scene.
The map view can be locked in the desired position to avoid accidental repositioning. This can be done by clicking into the map space, and then checking the Lock Map View box in the editor panel.
To adjust the size of the map view, single-click on the frame that you want to adjust. Use the stretch tools on the edges of the rectangle to click and drag the box to adjust to the desired size.
Multiple map views can be added to the same report page. To add an additional view, first click in the grey/negative space next to the report cover. In the editor panel on the right side of the screen, select Map View from the Elements section. Click and drag on your report page to draw a rectangle where you would like the new map view to appear.