One way would be to delete the autocorrect entry for (c) by
clicking on Tools | AutoCorrect Options | AutoCorrect tab |
<click on the entry for (c)> | Delete | OK. Note that this will
delete the specified autocorrect entry in all of your Office
applications, not just in Excel.
Another way would be to turn off the AutoCorrect feature in Excel
by clicking on Tools | AutoCorrect Options | AutoCorrect tab |
uncheck the "Replace text as you type" box | OK.