How can I connect sftp via filezilla?

[angelbro]

client : aaa
domain : bbb.com
ftp user name : bbb.com (virtual directory : test/bbb)
program : filezilla

I can connect ftp by username (bbb.com).
And I can also connect sftp by username (aaa).
But I can not connect sftp by username (bbb.com).
I got message below.
Error:   Authentication failed.
Error:   Critical error: Could not connect to server

How can I fix that?
For your information I changed ssh port 22 to 9377. (and I didn't restart ftp, just server rebooted)

[MRatWork]

Sftp is using ssh username for access. It's why you can't access via domain as username.

[angelbro]

OK I got it. Thank you.

One more question.
Can I make additional ssh username to access each domain?
I think it's more safe that every domain has different ssh username.

[MRatWork]

OK I got it. Thank you.

One more question.
Can I make additional ssh username to access each domain?
I think it's more safe that every domain has different ssh username.

I think possible but not easy (need modified ssh dir). By default, if we create ssh account and then /home/<account> will be create.

[angelbro]

OK I got it. Thank you.

One more question.
Can I make additional ssh username to access each domain?
I think it's more safe that every domain has different ssh username.

I think possible but not easy (need modified ssh dir). By default, if we create ssh account and then /home/<account> will be create.

Thank you for fast reply.
I find a way while reading your reply.
But as you told, It's Inefficient.
So I do nothing.