If you are using a vivo phone, the method to set the default program is as follows:
OriginOS/Funtouch OS 4.0 and above: Settings--Applications and Permissions/More Settings--Permission Management --Permissions--Default application settings
Funtouch OS 3.0 and 3.2: Settings--More settings--Applications--Default application settings.
Funtouch OS 3.0 or below: iButler--Software Management--Default Software Settings.
The default programs that can be set are: input method, desktop, browser, photo album (gallery), music, video, message, email, dialer, and document.
Note: The camera default program only supports settings below Android 11.
For more usage doubts, you can go to the vivo official website--My--Online Customer Service--Enter manual and consult online customer service for feedback.