Please click here to log in to your account, you will need to use the email and password that you registered when setting up your account.
Once logged in to your organiser account, on your dashboard go to the event you wish to amend and click:
From the main menu, which will be on the left, or the top righthand corner, depending on the size of your screen, you will see the options for editing the ticket details under the Tickets heading, use this drop-down menu to click on Update ticket details in bulk
This will take you to a new page where you will be offered the following options for your tickets:
by selecting an option, you will be able to edit the details of the ticket, for example, setting an available form and until date, amend the details as necessary, and click on Update
If you wanted to try out the different options, I would recommend adding a ticket and setting it to Secret, your customers won't see the ticket and you can play with the functions as much as you need to and no one will ever know!