the only real way is to use an actual Text Box Clyde.
to do this
Click the Text Box button, located in the Text group on the Insert tab. From the menu that appears, choose Draw Text Box.
The Draw Text Box option is near the bottom of the menu.
Click where you want one corner of the text box to appear and drag to where you want the opposite corner.
Drawing a text box is similar to drawing a rectangle.
Release the mouse button and then type your text.
This will keep always the same formatting for you.
to lock formatting, You can set Restrict Formatting for the document.
the guide on doing this you can follow hereClick Me
But it is not as restrictive as a PDF is.