Rows and Columns are numbers in Microsoft Excel

Why is Microsoft Excel displaying all my rows and columns with numbers instead of the standard R1C1 reference? I tried changing the settings back to the default by clicking on ToolsOptions and selecting R1C1 reference style under the General tab, however, this didn’t make a difference. Does Excel have a similar default document template or are there command line options to repair the Excel template? As a temporary solution I opened a previously saved Excel file with R1C1 row/ column references and this seems to have corrected the problem, but I’m still stumped and quite baffled as to how this problem started.