When I enter the parent account, the content of the account field change automatically to the parent account.
I agree, this sounds a bit cryptical :-)
Example:
I create an account with account name Comp-A
I create another account with account name Comp-B
Go to account Comp-A and change the field parent account to Comp-B. The moment the field parent account is filled with Comp-B, the contents of the account field change to Comp-B as well.
Is this a known bug in Zoho CRM?