Whole numbers in Excel showing as decimals (e.g. 1 = 0.001)

Hello,

Just recently I began having problems with numbers in Excel - I have never had these issues before, and have been using Excel for many years. I am using Office 2021 on a MacBook Pro.

The first issue was that instead of a period as a decimal point character, Excel suddenly started using a comma.

I reside in Germany, so I suspect that had something to do with the "comma instead of period" issue (Germany uses a comma as a decimal place, and a period as the 'thousand' marker).

I seem to have resolved this issue, but I am not certain how I did it - possibly in Excel Preferences.

The second (and more problematic) issue is as follows:

When I enter a whole number, such as "1", it appears as 1/1000s, i.e. "0.001" .

I have checked the cell formatting preferences: General and Numbers are the default settings.

I have opened new (blank) documents offered upon starting Excel, and they all have the same problem.

Today I uninstalled and reinstalled Excel, the problem persists.

So I suspect this might have to do with Microsoft possibly perceiving that I am in Germany, and changing number formatting in Office programs on that basis? There should be an option for those of us wanting to maintain North American formats, to control this manually, if this is the case.

I'm quite frustrated that Microsoft now only offers online support. Chat support is much too slow.

I am writing here in the hopes that this issue might be quickly and easily resolved - budget work awaits!

Thanks for any effective assistance you might be able to provide!