How do I set a bullet style as default in Microsoft Word 2010?

The reason why Set As Default... is greyed out when accessing the font dialogue box through the 'font' option in Define New Bullet is because the same font dialogue box is used for this function, and also if you were to bring up the font dialogue box without going via the 'bullets' option first.

Put simply: the same dialogue box is used in both instances; the only difference is that if you access the font dialogue box via the bullets option, it is assumed that you do not wish to make any changes to the actual font settings of your document other than those which will affect the bullets, hence why it is greyed out.

To confirm this, if you bring up the font dialogue box directly Ctrl + D, you will notice that the Set As Default... button in the lower left hand corner is fully clickable and is not greyed out. This is because you have accessed it directly, which implies that you wish to make changes to the font style within the document itself (not specifically for the bullet-type) and thus provides the option to even change the default font for all future documents.

Furthermore, if you wish to define a pre-defined set of bullets to use across particular Word templates - Normal.dot/Normal.dotm included - then my advice would be to set the bullets to precisely how you want them to look and function, and then set the template to be used across the Normal.dot/Normal.dotm template. This means that any future templates that you wish to create will have access to the newly-defined bullet styles and will make the task of creating separate templates much smoother as the resources are all readily available.

To achieve this, perform the following steps (MS Word 2010):

1. Select the 'Developer' tab. (If this is not visible, then follow these steps);
2. Select 'Schema';
3. Towards the lower left-hand corner of the 'Schema' window, select 'Organizer...'. This will now bring up a list of all styles active in the current document, and all available styles in the Normal.dot/Normal.dotm template.
4. Select your newly-created style from the left-hand pane and click 'Copy' to copy it across to the Normal.dot/Normal.dotm template.

From here, you may create new templates which will all have access to the new bullet styles with minimal fuss.

Hope this helps.