I'm using VirtualBox to run Ubuntu Desktop 16.04. I shared folder and can access it from any Windows user, but I really want so only one specific user can access it and others will get denied. I know how to set password to that share but that's not it. I tried to search similar question all day but without results. Thanks!
I don't understand this part of your post:
I know how to set password to that share but that's not it.
It's not clear to me how one sets a password to a share.
Anyway, the classic way of doing this is to edit
/etc/samba/smb.conf and create a share definition that in its simplest form looks something like this:
[ShareName] path = /path/to/folder read only = no valid users = bob
Then restart smbd:
sudo service smbd restart
You would have to:
** Create a local user on the Ubuntu box named: bob
** Then add him to the samba password database:
sudo smbpasswd -a bob
Note: If you created the shares from Nautilus ( Files ) you need to go back and unshare it in Nautilus. Nautilus as currently configured does not have the ability to specify only one user for access.