Move the cursor after the last word on the third page, then click Insert, click the separator, and then click Next on the pop-up picture box. Then press the following operation in the footer of the first page: Insert, select the page number, click the format, find the Greek alphabetical order (Ⅰ Ⅱ Ⅲ ...), and click OK. So the Greek letters are in front, and Arabic numerals are used from the fourth page.

hope this helps