I am trying to merge together two polygons to create a polygon of the whole UK. However, I can't seem to select more than one polygon. Also it seems to be random as to which polygon will be selected. It's not always the same polygon, but I can only ever select one polygon at any one time.
I have tried toggling the edit button but that doesn't work either.
(If someone has a shapefile of the UK I can use then I won't need to do this)