Why can't I set a report as default on Browser User Interface?
Browser User Interface (BUI)
Oracle B2C Service versions below August 2015
Unfortunately to get "Set as Browser Desktop default" feature on Browser User Interface (BUI), your Oracle B2C Service smart client version must be at or above August 2015. Therefore, to get this functionality in the Browser UI you must upgrade your Oracle B2C Service site to the most current version.
For information on upgrading, refer to Answer 1124: Requesting an Oracle B2C Service Update.
Although Browser UI (BUI) can be thought of as single version, the Oracle B2C Service smart client is not and may be missing functionality that is available in the version of BUI.
"Set as Browser Desktop default" is one functionality that is not available to BUI until Oracle B2C Service version August 2015.