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