Why can't I select a different tuning?

On the Free tier, Standard — E A D G B E is the only tuning you can pick. The other tunings are still in the list, but they're greyed out and marked Pro. Changing tuning is part of Pro.

What Free includes

Free gives you the full chord tool in Standard tuning — search any chord, read the diagrams, build a progression, and play it back. What's held back for Pro in this area is:

• The 15 other preset tunings — Drop D, DADGAD, Open G, and the rest. They show in the Tuning list but are greyed out with a Pro label.
• Custom tunings — the Custom Tuning button is marked Pro and can't be opened on Free.
• The capo — the capo controls are marked Pro too. See how the capo works.

Unlocking tunings

Pro is a one-time purchase, not a subscription — pay once and all tunings, custom tunings, and the capo are yours. See What's the difference between Free and Pro? for the full list, and How do I upgrade to Pro? for the steps.