This article will teach you how to make a default Sprint on the Agile board.
Activate sprints by default
Firstly, you need to make a Scrum board (with Sprints) to be a default one for the Agile board (and not the Kanban). To do it, please go to Administration - Agile. And here, just make sure to enable the "Activate sprints by default" feature as shown in the picture below.
Active status
Now, you have to go to the specific project that you need to apply the changes and then select Settings. Afterward, Sprints tab.
Here, pick one sprint and make sure to set Active for the status of it.
Important: Only one Sprint can be marked as Active as only one can be set as default. If some Sprint is already set to be active (default) and you pick another one and make it active, then the previous one automatically changes to status "open".
When you make these changes, then the project list with sprints will look like this:
And then, when you open the Agile board, as expected, the 3rd Sprint will be automatically chosen: