For signing into Easync itself, use the password reset on the login page.
But most "incorrect password" reports in support are actually about your fulfillment (Auto Ordering) account, not your Easync login: when the Amazon password saved in Easync is wrong, orders stop and tracking won't update.
The fix is to change the password in your Amazon account, then enter the new password in Easync under Fulfillment Accounts (the fulfillment methods / AO account settings), and tell support in the chat once you've updated it so they can re-run the affected orders.
After the password is corrected, the stuck orders and their tracking are reprocessed on the backend.