Changing character set of existing databases

Hello,

I made a mistake an got a character set in SQL_ASCII as the defaut
encoding type :

$ psql -l
           List of databases
      Name     |  Owner   | Encoding
--------------+----------+-----------
  cmp_crm      | openerp  | SQL_ASCII
  cmp_crm_demo | openerp  | SQL_ASCII
  cmp_testcrm  | openerp  | SQL_ASCII
  postgres     | postgres | SQL_ASCII
  template0    | postgres | SQL_ASCII
  template1    | postgres | SQL_ASCII
(6 rows)

I need to get them in UTF-8. ->
1) Can I modify these existing databases to switch them into UTF-8? How?
2) Can I modify the defaut character set to create further databases in
UTF-8 by default?

Thank you so much,
nm