The POV default member initilization will explain what POV member will be used in what situation. According to the POV filters used for the logged on user (regular or light user).
CONTENT
Default Member in case of Storyboard play
The member which the bookmark was created with
If that member is not allowed or not available, the default dimension member defined by a special variable is taken (see Default Dimension Member below)
If the default dimension member is also not allowed or the special variable doesn’t exist, the first member from the POV dropdown is taken
Default Member in case of Central Initialization
The member which was selected in the previous report
If the reporting session is just started, the default dimension member defined by a special variable is taken (see Default Dimension Member below)
If the default dimension member is not allowed or the special variable doesn’t exist, the first member from the POV dropdown is taken
Default Dimension Member
Default dimension member is defined by special variable: