use Northwind

Alter database [db_track]
set change_tracking=on
(change_retention=3 days,Auto_cleanup=on)

i m running the above  command i m geting the ERROR AS

Msg 5011, Level 14, State 5, Line 3
User does not have permission to alter database ‘db_track’, the database does not exist, or the database is not in a state that allows access checks.
Msg 5069, Level 16, State 1, Line 3
ALTER DATABASE statement failed.

how do i check that which user is logged in.

Regards,
RINO