To change the priority of the default content page or to add a new default page:
1) Login to IIS. Select the domain.
2) Right click on the domain.
3) Click on properties.
4) Select the tab "Document".
5) To add a new default content page, click on Add, and enter the page name with extension.
6) To increase the priority of default content page, select the page and click on Move Up.
7) To decrease the priority of the default content page, select the page and click on Move Down.
8) Click on Apply to save the settings.