[Using MacBook Air, OSX 10.7.5, MS Excel version 14 (100825)] My mac is set to American standards - uses periods to indicate decimals, commas for thousands separators, etc. I've just received a European excel file using commas for decimals and I'm trying to figure out how to change it to periods for decimals. If I go to system preferences - language and text - formats - numbers, it shows the standard US preferences, so I think the solution is in excel. Excel 14 does not have a "tools-options" command. Format - cells - accounting in Excel does not often an option to make that change, it simply shows the commas as the default for this spreadsheet. Excel help says: "Date, time, and number formats When you enter dates, times, and numbers, Office displays them based on your settings in Mac OS X Language & Text preferences." That is true when I create files, but when I'm using a file created using other formats, my settings in OS X Language and Text preferences do not override the settings used to create that file. I can't find anything in Excel preferences that lets me change the format of a file when it differs from my defaults. Does anyone know how to do this?