For https://wordpress.org/support/topic/how-to-replace-my-account-option-in-mobile-veiw/

edit-account-link.php

	function storefront_handheld_footer_bar_account_link() {
		echo '<a href="' . esc_url( 'http://my-custom.link' ) . '">' . esc_attr__( 'My Account - custom link', 'storefront' ) . '</a>';
	}