You can configure the numeric values format in documents by setting the decimal separator for numeric values and the thousands delimiter for numeric values by preference.

The separator, in decimal separator for numeric values can be a point or a comma. In case of thousands delimiter for numeric values the separator can be a point, a comma or a space. The fourth option would be 'no separator'.

Do the settings by accessing 'Configurations'

Then 'Default values'

Click on 'Number formatting'

If you want to change the number format settings on an individual invoice, you can set them from the invoice edit page, 'Advanced Settings' section.

In the example below you can see what the values on the invoice look like in the case of the comma and point separator.