I'm assuming you want to change the representation of decimal numbers from xxx,yy to xxx.yy. This is actually an operating system function having to do with localization. It sounds like your computer is set to use a comma as the decimal separator (between whole and fractional part) and the period as the thousands separator (one Million being 1.000.000) - but you have a keyboard that assumes the opposite!
In Windows 10 (per your profile), you want to:
- Navigate to 'Control Panel > Clock, Language, and Region'.
- Click on "Change Date, time, or number formats (Under the "Region" heading)
This will open a pop-up dialog
- Click on "Additonal settings ..." button - this will pop up another window
- Be sure you are on the "Numbers" tab - it should look like:
- Change the "Decimal Symbol" to a period
- Change the "Digit Grouping symbol" to a comma
- Click "OK" (Customize Format window will close)
- Click "OK" again (Region window will close)
You might have to then restart SketchUp - or restart your computer to have the changes take effect.