I started typing some text using the Text tool, but it is too wide. I have resized my text box, but when I try to type in it after resizing, it reverts to its original size. How can I keep the new size?

Select the text box, and choose "Edit > Wrap Text" from the main menu.
Note: If you use the text box tool to drag out a text box, instead of just clicking to create a text box, Wrap
Text is the default behavior.