[Samba] Read Write Permission

[Dino Chopins]

Hi Everyone,

I've setup file server for my client with these schemes :
1. Samba server is on CentOS box
2. Every user has their Unix accounts
3. Every Unix accounts have their mapped Samba users/accounts with same name
4. They can get access to some shares, eg :
[Accounting]
        path = /public/accounting
        valid users = alexander, bernard, charlie, david, eugene
        admin users = alexander
        read list = eugene,
        write list = alexander, bernard, charlie, david
        read only = No
5. I use Ubuntu clients to access to this share with a valid user listed above

My problem is, when one of this user let's say alexander created a
file with OpenOffice and save this file the user:group created is
alexander:alexander and permission is -rwxr--r-- (744). Thus, other
user such as bernard cannot open the file created by alexander. How
can I change / set a default permission to -rwxrw-rw- (766) ?

Regards,

Dino