I'm using QGIS 2.6 and am struggling to get three different maps in one print composer. Better explained, one map with the county, the 2nd closer viewed with the town and the 3rd with the actual woodland. Its for a uni project however I can't seem to get beyond loading the 1st map. Iv saved it, I've clicked the lock layers but when it comes to reloading I just get a blank box reappear. Also, when I have the first map put on the composer, if I switch back to QGIS to load up the 2nd, print composer just closes. Any ideas?
If you are just trying to view the same dataset at three different scales (woodland, town, county), then use the overviews in the composer. Set the woodland to the main map view, and then use overview to show at the other scales. You can also use layer locking so that the map composer is showing different combinations of layers to the main map canvas. https://www.qgis.org/en/site/forusers/visualchangelog260/index.html#feature-multiple-overviews-for-a-map-item shows the change that was implemented in 2.6 to allow for multiple overview maps
The reason why the composer closes is because it is linked in to the project instance you are working in. The main QGIS window is not a map per se, more of a data viewing area (the "canvas"). The composer provides functionality to make a map (in the traditional, paper map sense) from the data currently available in the main QGIS instance