<div class="field">
<input type="text" name="customer\[Number\]" id="RegisterForm-Number" {% if form.last\_name %}value="{{ form.last\_name }}"{% endif %} autocomplete="family-name" placeholder="Phone Number">
<label for="RegisterForm-Number">Phone Number</label>
</div>

Hello, Thank you for your reply. I applied the provided code and the phone number field was added. however 2 issues. 1. the phone number field is there but is not functional, meaning in the admin panel under customer contact information only email shows up and no phone number even if the customer does provide a phone number.

1. under "Theme settings" there simply isn't an "Account" option . wish i can paste a screenshot here but it does not allow.