Hi GuitarDude,
When you click the edit button it should automatically highlight everything in your status, like in the picture below:
From there you can either hit backspace to erase everything at once, or you can click somewhere in the highlighted area and that will give you a cursor to use to edit your current entry. Unfortunately, there is a bug right now that prevents you from seeing your cursor past the first line of text if you type more than one line, but it will still accept an extended entry.
You might need to restart your browser if you are having trouble getting it to highlight when you click edit.