How to underline spaces?

More likely is that some documents have a per-document compatibility setting in **Word->Preferences->Compatibility.**There is one for "Draw underline on trailing spaces" which might cause it.

Thank you very much--that is exactly it. I had looked in Preferences but would have never thought to look in Compatibility.

David

What is the purpose of trying to underline a space? Why not just type the Underscore character instead? Or -- better yet if more than a single space --  use a Tab with an Underscore Leader?

Peter is correct about the Compatibility preference, but that's a 'throwback' to the days of fixed width characters. The default for Word documents is to not underline spaces because the space bar is intended to generate white space. By definition a space is exactly that -- an interval containing no displayable/printable characters.

Since the introduction of Proportionally Spaced Fonts on personal computers, use of the space bar for anything other than a standard space between words or between sentences generally is not accepted practice. The amount of space allocated with each press of the bar can differ depending on a number of variables & cause inconsistency as well as other formatting/layout issues... especially if stringing together several consecutive presses of the bar.