In Strategy Web 9.x, on Web Administrator page, it is possible to specify the Path to Strategy Office Installation, as shown below:

In certain situation, when user tries to clear this text box or set "Lang_xxxx/officeinstall.htm"(xxxx is corresponding language code when "Automatically append locale-specific path" check box is checked) as default value, after click save, a default web service URL is appended automatically.
This default URL is hard coded in below file, user is able to modify the "URL=" parameter to specify another default value or leave it blank in order to set "Path to Strategy Office Installation" to "Lang_xxxx/officeinstall.htm". Restart the Web Server for these changes to take effect.
<Strategy Web Path>\WEB-INF\classes\resources\office.properties