Unfortunately, Firefox doesn't have a way to disable built-in keyboard shortcuts. Websites can intercept ''most'' shortcuts, including Command+B, for their own purposes. If it's not working in Firefox (but it does work in other browsers on the same page), here are two possible reasons: (1) The site does NOT have permission to override built-in keyboard shortcuts. Here's how you can check on this: While you are on a page on the site, call up the Page Info dialog using one of these methods: * Command+i * (menu bar) Tools > Page Info When the dialog comes up, click the Permission icon at the top to show that panel. Scroll down to "Override keyboard shortcuts" and uncheck the "Use default" box, and then select '''Allow'''. (2) The site uses older code that isn't compatible with Firefox. This could be difficult to fix. Do you want to mention the site that has the problem in case anyone knows whether this is the issue? (Or you could do some searches to see whether they are known to have this issue for other Firefox users.)