Cannot select cells

Cannot select cells

I am using the Android app and don't seem to be able to do the most basic thing: selecting a group of cells. Whether for the purpose of formatting or generating a chart, for some reason I am not able to select the cells I wish to format or chart.

When I try to select a cell and extend to a group of other cells, the only thing that sometimes happens is the contents of the first cell are copied to all the other cells. Either that happens or nothing happens.