This below recommendation fixed the problem of showing 'Preferences' link on the header panel in Portal.
But now user still can't set the WEBI report viewing ability in HTML Mode. When user clicks on "Preferences" and click on "Web Intelligence", I see this message:
"You do not have the rights to execute this action. If you rewuire the right, contact your system admin.
Login to CMC as Administrator.
Go to "Users and Groups" management area.
Go to "User Security" of required user or Group for which you want to show Preferences button.
Click on "Add Principals".
Select the appropriate User[s] or Group[s].
Click on "Add and Assign Security".
Explicitly grant the right "Change preferences for objects that the user owns" to the user.
Click Apply and OK.