Click your left mouse button and hold it. Still nothing special to look at. Drag the mouse down to Cell E6 and let go. Cells E2 through E6 are highlighted. A pull-down menu appears.
Several options are available.
Scroll down using the downward arrow. The list of formats scrolls on the screen. A new selection for decimal places appears. The pop-up window disappears, and all the numbers have been change to percentages with one decimal place.