[PROBLEM] SAMBA with USB mountet Device under RC3

[bibu]

To be honest, I'm not sure if I get it properly and I can't play with this RPi too much (it isn't mine). However, I did many restarts before my changes (every time was read only) and after (now no problems, remains read write). Also, I had done all methods like changing owner, changing mode etc., so my config may not be the same as the clean one. And really, shell isn't my strength I just know some commands I found on the Internet but that's all. Figured it out by logical thinking and --help
Sorry I couldn't help you more. Maybe there are some commands I could type but I'd rather not change anything there. Maybe file system is relevant – it is ext4.