This may come in handy for those who always look for exact matches including case. Sure you can always just click on the “Match case” check box in the Find bar. But for those who always use the feature, this little tweak will make sure that little box is checked by default.

• Access the about:config page.
• Find the accessibility.typeaheadfind.casesensitive preference name
• Double-click on it to change the integer value to 1
• Click on OK
• Close the about:config page/tab
• The changes take effect instantly

I, myself, chose to leave it in the default setting for flexibility.