• To save the credentials for a given share from management studio run 

EXEC master..sqbutility 1082, '\\share\backups', 'login', 'password' 

• To delete the credentials

EXEC master..sqbutility 1082, '\\share\backups', '', '' 

• To disconnect all existing connections

(in situations where a network failure has occurred, and all existing connections have become invalid and needs to be refreshed)
EXEC master..sqbutility 1082, '<disconnect>', '', '' 

The share names are considered to be case insenstive.

The SQL Backup Agent will choose the longest match  available,

so for example to copy a file to //share/backups/pubs 
and there are details for 

//share/back

//share/backup 

//share/backups 

//share/backups/pubs 
the engine will choose the longest match in this case //share/backups/pubs 

(NB. The passwords are obfuscated not encrypted.)