Hi Andrew,
Thanks for using our plugins and welcome to the forums! I think I can help you with your questions.
To change the default value to one, the best course of action would be creating a template override. You can find more details on this topic in our Themer’s Guide – https://theeventscalendar.com/knowledgebase/themers-guide/
Basically you will need to create an override for this file:
wp-content\plugins\event-tickets-plus\src\views\eddtickets\tickets.php
and make some changes to line 66, which looks like this:
echo '<input type="number" class="edd-input" min="0" ' . $max . ' name="quantity_' . esc_attr( $ticket->ID ) . '" value="0" ' . disabled( $must_login, true, false ) . '/>';
and change the value to 1.
how can I limit it to just one per checkout
The cart and the checkout is already handled by EDD, so you would need to look around in their extension library if there is something for this, or in their support forums.
Let me know if the above trick helps.
Cheers,
Andras