You can change the availability schedule that an event references by editing it in the event level settings. To do this, visit your event type dashboard and click on the event you want to edit. Once this is done, a page displaying your event's settings and parameters will load.
You'll notice that towards the left-hand side of the screen, there is now a tab that says availability. This tab is right underneath the event set-up tab. Clicking on the availability tab will take you to a screen that displays the availability schedule connected to that specific event.
You can then click on the drop-down menu to switch out availability schedules. Remember, as always, to click on the save button in the upper right-hand corner of the screen to ensure that your changes are applied.