problem with permissions 777 mode

Hello everyone,

I have some problem with my zyxel nas326 nas.
I create "myuser" who is part of "everyone" group. If I create another group (for example "mygroup")
the "myuser" don't have full access to files. Now every file I create is with full permissions 
-rwxrwxrwx    1 mysuer     everyone       843 Mar 29 18:57 test.txt <- copy from mycomputer file

I would like all files in my share to be with 755 permission and for one directory (mypictures) to be with
user:myuser, group:other So I can share it over ftp to other people.
What I should to do to fix that?

Actually I can access my files only with this configuration:
https://snipboard.io/Az0cjn.jpg

With this settings I can't access via samba using my correct credentials.
https://snipboard.io/NEVpBG.jpg
https://snipboard.io/CeHqO6.jpg
https://snipboard.io/50nybv.jpg


Thanks in advance !


#NAS_Apr_2020