I'm using version 3.4.1 and have changed the font of the blog title and page menu bar. In Internet Explorer, the changes both look fine but in Firefox, the blog title's OK but the font on the page menu bar has changed but not to what it should be. Why would this be so and how do I correct it? Thanks

what is the url?
If you change the font to another, do they both see the same font?
is it a web safe font?
what font is it?
what is the exact syntax you are using?
where did you put it (in what option)?

http://www.thursdays-child.com
True type font, tried another one and had same thing, i.e. OK in IE, page menu bar not changed to what I wanted in Firefox.
Changed blog title in 'Style and edit Header Area':
margin: 0;
padding: 0;
letter-spacing: 2px;
line-height: 1.2em;
font-family: "Columbus";
font-size: 360%;

Changed pages under 'Page Menu Bar:
20px "Columbus", weight: bold

Thanks

not all browsers support all fonts which is why you need fall backs. this is not theme related, you should do a google search and see
1) is supported on both browsers
2) does it have to be installed on the users computer

take a look at http://www.w3schools.com/cssref/pr_font_font-family.asp for info on the font families

(I designed a site in safari on the mac and used a 'script' font and it looked fantastic...well I thought so, then I looked at it in IE and it was awful because IE did not support or even have that font installed)

But if Firefox doesn't support this font, surely the blog title wouldn't look fine?

Changed pages under 'Page Menu Bar:
20px "Columbus", weight: bold

this is invalid syntax

Also Columbus is not a web safe font. If order for a font to show it has to be installed on the computer that is viewing the site unless you use special font plugins. You may see Columbus when you look at the site but many others will not.

OK, many thanks both. Can you tell me what the correct syntax is? Also, can you recommend a font plug-in please?

You can get the syntax for fonts at w3schools.com and I would do a search on wordpress.org for a font plugin. I haven't looks for a font plugin in awhile and prefer to use standard websafe fonts as you can have anti aliasing issues with font plugins. This means the fonts don't display clearly on some computers.