I encountered a similar problem, having a "username" field placed under a "name" field. That username field was auto-filled with a age. It came from another form on the same site that was displaying a "age" field group just below the "name" field. So chrome stored its auto-fill values in that order.
<input type="text" name="username" readonly="" onfocus="this.removeAttribute('readonly');">
The other way you can change the form field order.
One thing you can do is ask your users to disable saving the password for your site. This can be done browser wide or origin wide.
Something, else you can do is to force the inputs to be empty after the page is loaded (and after the browser auto completed the fields). Put this script at the end of the `<body>` element.
userIdInputElement.value = "";
userPasswordInputElement.value = "";
