Sometimes you may hit escape to switch to command mode, and find that the words INSERT MODE still appear at the bottom left corner of the window (as it does when in INSERT MODE with some setups). If this happens, press escape again to be sure you are actually in command mode. If the words still appear in the lower left corner of the window, you may want to ``refresh" the screen by pressing the control and l keys at the same time. (That is the lower-case letter ``l" in case you were not certain.) Now, if you are not in insert mode, the words stating otherwise will disappear from your screen.
IMPORTANT!! Do NOT use the arrow keys to move around your text while in insert mode!! Strange things will happen!! This can be frustrating! In time, you will learn to escape from insert mode FIRST, before moving around in your file to make any necessary corrections.