In MyOffice Spreadsheets, you can set the thousands separator you need in number formatting. Follow these instructions:
Select one or several cells for which you want to set the separator.
Open the format editing window in any of the following ways:
select the command menu item Format > Number Format;
in the toolbar of the Table context tab, expand the list of formats and select Parameters;
Right-click the selected cells and execute the context menu command Number format.
In the window that appears, select Number and check the Separate groups of digits checkbox.