Hi Klein sounds like you have some Samba experience already
so you probably know about setting linux/samba permissions.
I found the tricky ones are when descend into directory perms are involved. Remember this goes up to the share root.
And also when perms change due to file editing between users, so group membership is important here.
Could I suggest a common-mode setup approach. . . use smb.conf OR caja-share for your config on all pcs. Caja-share sets perms like: " usershare_acl=S-1-1-0:F "
in its share config.
On my network I prefer "easy" permissions like this share config in smb.conf:
comment = Dads Share
path = /home/richard/myshare
guest ok = yes
browseable = yes
create mask = 0660
directory mask = 0775
force user = richard
read only = no
The "force user" and "create masks" are a catch all to keep me sane. The "browsable" and "guest" entries make it easy to find. This may not be secure enough for you, adjust to taste. Hopefully some of this is helpful. Richard.