The find and replace function in Word is fairly intelligent when it comes to capitalization.
Unless you have the match case option on, finding a character string will find all occurrences regardless of their capitalization. For example if you find "poll" all occurrences of "poll", "Poll", and "POLL" will be found. In many programs a request to replace this with "survey" would result in all of these occurrences being replaced with the replace string exactly as typed - losing all capitalizations. Not so in Word which will maintain the capitalization as best it can.
A request to find all occurrences of "poll" and replace them with "survey" will therefore result in "poll" being replaced by "survey", "Poll" being replaced by "Survey", and "POLL" being replaced by "SURVEY".
The same should be true of any other find and replace request. If this appears not to be happening then expand the find and replace box by selecting the More button. This will display a variety of additional options at the bottom of the dialog box. The most likely option to affect the capitalization is the "Font" option. Resetting this to its default values should restore the capitalization to the behaviour described above.
The other instance where the capitalization may not be as expected is if the find string is partly capitalized eg "POll" or "POLl". Such capitalization is most likely incorrect in the first place. Word will do its best to correct this capitalization when you use replace but may not always get the capitalization that you intended.
This article written by Stephen Chapman, Felgall Pty Ltd.