In order to copy over events from another season to another season, you MUST set the current Season you are copying to to be default. Please read the below article on how to do so:
Click Copy Events on the top right of the page.
Select the Season you wish to copy from.
Select the events you wish to copy over using the checkboxes on the left. Click Copy Selected Events. Your selected events will be copied over to your current (Default) season. Be sure to edit the dates and information of your copied over events before opening it up to the public.