Change default output font globally

Question

I'd like to change my default output font to "Helvetica Neue" in version 10.

The following shows the only thing I have found in Option Inspector, which would appear relevant:

Where I've changed FontFamily to "Helvetica Neue", the "Apply" button does not become enabled when I make the change.

Neither does the change appear to have any affect in a notebook.

If possible, I'd like to change this globally rather than create a dedicated StyleSheet.

Specifically, I use Grid, Column, and Row for formatting output a great deal and would rather not have to specify a font every time I use them.

For graphics, I've also tried to change AxesStyle and LabelStyle from the Options Inspector as per Mr. Wizard's recommendation in his answer to:

Set default font for Output

and have the same issue in that the Apply button never enables.

I guess this leaves using something like:

SetOptions[$FrontEnd,
  PrivateFontOptions -> {FontFamily -> Directive[FontFamily -> "Helvetica Neue"]}
]

(Not certain the above will work or what it will affect. I'd like to know before trying it and understand how to reverse it. Please advise).

Or...

   SetOptions[$FrontEnd,
      GraphicsBoxOptions -> {AxesStyle -> Directive[FontFamily -> "Helvetica Neue"]}
    ]

Thoughts?

Suggestions?

Note: I don't think the following answer my question, but they may provide some context.

Set default font for Output

Change font for the whole notebook

Answer 1

The most direct way is to customize the StyleSheet.

To create a new StyleSheet to use with Mathematica, open a notebook and select Edit Stylesheet... from the Format menu. This brings up a template, and existing styles can be modified by choosing the style from the pull-down menu on the top left of the template. The style is inserted in the template with the cell bracket selected. Modifications to the style are made directly from the Format menu. If the stylesheet is intended for use with other notebooks, click Install Stylesheet on the top right of the template and follow the instructions on the wizard.

Some additional information on the creating the StyleSheet is here.

Take care to save the new StyleSheet with SaveAs, rather than Save, even if it has already been once saved.

It would be a good idea to create a custom StyleSheet on the basis of the existing one, but not to replace the existing one with the custom. The drawback is that you will always need to change the StyleSheet from the Default to the Custom upon creating a new notebook. The advantage is that you will have the Default template intact in case.

If you need some more help on the modifying the StyleSheet, just ask.

Have fun!