I use MS Excel for Mac 2011 on OX X 10.11.6. I am a home user. I keep personal accounts on Excel. I also have Chinese fonts on my computer that I use for my work (as retired professor of Chinese studies).

For some reason that I don't understand the default font in my current Excel files has become a Chinese font identified as "新細明體 (Body)". That is a Chinese font that I have used for some work in MS Word, but never (that I remember) in Excel.

An extremely unwanted result of this situation is the fact that, even when the option to insert Chinese text in Excel is turned off, if I enter a date in the left column of a spreadsheet, using the format, for example, 1/1 , it converts to 1 月 1 日, which is the same meaning in Chinese. I don't want Chinese characters to show in such spreadsheets, which are simply my daily register of household cash flow.

I have gone to Excel, Preferences, General, Body Font and manually selected "Cambria" as the default Body Font. So now "Cambria" appears in new worksheets as the default font. Nevertheless, even in a new worksheet, when I enter a date by the formula "1/1", then hit Tab to move to the next box, the date is displayed again using Chinese characters as "1 月 1 日". Very annoying.

How can I effectively remove the Chinese output when it is not wanted?