You have set up your account on HeySummit and you're running multiple different events. You can see that every event has an original HeySummit subdomain when you first create it. Now you are wondering if you can use the same custom subdomain for all of these events instead.
Custom domains can be created per each summit, not per account. You will need to use these steps for setting up a custom domain for each event.
This is because of the way that CNAME records are set up on your DNS provider. It's important there are no other CNAME records that already exist in your account for the subdomain you want to use.
For example, if you want to use summit.mydomain.com, you need to make sure that you've not already created a CNAME record for that path. If one already exists you can use a different subdomain (example: summit2020.mydomain.com).
Reusing a subdomain you used for another HeySummit event
If you have an event that you ran in the past and you want to use that exact custom subdomain again (e.g. summit.mydomain.com) for an upcoming event, you could switch it out.
Head to the dashboard for your previous event and navigate to Event Setup > Settings > Event Domain.
Delete what you have entered under the Custom Domain field (e.g. summit.mydomain.com). If you leave it blank, the event will be accessible via its original HeySummit subdomain seen at the top of that modal. If you want to create another custom subdomain for this event (e.g. summit2020.mydomain.com), follow the steps in the doc above after deleting what was in that field.
Head to the dashboard of your new event and navigate to Event Setup > Settings > Event Domain.
Enter your subdomain under Custom Domain (e.g. summit.mydomain.com).
Press Save.
Note: It's very likely that you previously shared your custom domain in relation to your old event on social media or via email. If someone clicks that link after you've switched the subdomain to a different event, they will be led to the new event. You might want to email attendees of the old event with the updated link to that event. You can do that using HeySummit's one-off email feature or externally.
Making your event evergreen
Instead of creating a whole new event and switching the domains out, you could consider making your original event evergreen.
Evergreen and non-evergreen summits start exactly the same way - they both require you to enter a Start Date. If you make the event evergreen, you don't get an End Date. It's the perfect solution if you intend to run a long-term webinar or speaker series to drive your inbound marketing efforts. An evergreen summit is intended to stay open for registrations over the long term. It also allows talks and content to be published periodically.