How can i change the difficulty level?

[CitizenOfTheWorld]

I remember when i played closed beta i was able to change the difficulty of the trial, how can i do it now?

[Jalir]

You have to unlock them sequentially. The different difficulty options are in the form of the additional variators that get added on as you unlock them.

[Walker☻//︻ ---]

? WUT? you dont...

[Rabby]

That has been changed from the beta, now you complete the main trial and then unlock a harder stage that has "modifiers". More modifiers there are, harder the stage is. (Ex: Deadly enemies makes enemies more stronger and more aggressive; Limited hidespots makes hiding spots appear less frequently; Deadly Prime Asset makes Prime Asset one shot you, etc.)