(In Word 2007 click the Office button and then click Word Options.

If it doesn't, then you should check to see if Shift+F3 has been customized within Word. That should do it you should be able to jump into Word and the function key should work as you expect. Delete anything that may appear in the Shortcut Key box.Windows displays the Shortcut tab of the Properties dialog box for the Excel program. Right-click the Excel program and choose Properties from the resulting Context menu.(You need to find it in the Start menu hierarchy, not within the Windows Explorer.) Within Windows, click the Start button and 'drill down' until you find the Excel program.Use these steps to correct the situation: This programming overrides anything that the function key may do within Word. If Shift+F3 still opens Excel while Word is closed, then the function key has been programmed within Windows to start Excel. The easiest way to figure out the level at which the function key is operating is to just get out of Word (close the program completely) and then try the function key. If there is a conflict between the purpose of a particular function key in Windows and the purpose of that function key in Word, then the purpose in Windows takes precedence.

Function keys can have various purposes within Windows itself and within Word. The first thing to check here is at what 'level' the function key is operating. He wonders how he can reset the Shift+F3 function key so it works like it should work. Now when Peter presses this function key it makes Excel launch. Peter noted that up to some months ago, while working on a Word document, he could select some text and, by pressing Shift+F3, change the case of the selected text.

Key command to change case in word