How do I underline on Mac key board

The keystrokes for Mac are essentially the same as on Windows with the difference being to use the command key (macOS) instead of Control (Windows). Therefore, to underline, select text and the use the keyboard shortcut command+u.

Just to be clear, are you needing to select a space character and underline it or are you trying to type the underscore character? Now you have me interested in the "confidential password" part of your reply. If you have been supplied with a password that is something like "This_Is_The_Password" then those underlines are actually the underscore character on the keyboard (i.e. [shift]+[-]).

Yes. Spaces are just characters like all others.

May I suggest that using underlined spaces is typically a bad idea in most word processing applications where you are trying to create an area on a form that you intend for someone to fill in. Instead, try setting two tab stops, one where you want the underlining to start and another where it should end, then use a single tab character and underline that instead.

dunwoody wrote:

I don't know to use the following: (i.e. [shift]+[-]) to do underlining like you used in your password example though.

Is there some problem when you hold down the Shift key and then press the - key? It should give you _.

dunwoody wrote:

to underline a space

There really is no such thing as "underlining a space" in a password field. Instead you create a "low line" character via Shift -. What exactly do you mean when you say this "won't work". Do you mean it does not appear on the screen as _? Or it appears but the password doesn't work?

dunwoody, I agee with Tom that there is no way that a password can contain an underlined space as an actual character. The person that sent the password to you either meant to use the "low line" character, or, confusingly used that character to indicate that you should just type a space at that point in the password. Try just typing the password using spaces, ignoring the underlining.