Not a member yet?
Accounts are opened in person. Meet a teller or the owner in the city: they register you with your name, phone number and bank account, and hand you your 8-word phrase.
Lost your phrase?
Visit the exchange in person; only the owner can issue a new one. Your old phrase stops working the moment it is replaced.
Nobody from the exchange will ever ask you for your phrase. Keep it written down somewhere safe.