Learn Turkish: Sürekli şikâyet edeceğine problemi çöz. - Instead of constantly complaining, solve the problem.

This is the core structure of the lesson. It's built from the verb root et (used here in şikâyet etmek) + the future suffix -ecek + the 2nd person singular possessive -in (your) + the dative suffix -e (to). Together, the pattern -(y)AcAğInA attached to a verb creates the meaning 'instead of [someone] doing [that action]'.

I see two consonant changes in edeceğine. What exactly is happening there?

First, the verb root is et-. When you add the vowel-starting suffix -ecek, the t softens to d, making it ed-. Second, when you add the possessive suffix -in to edecek, the k softens to ğ, making it edeceğ-. Then the dative -e is attached at the end.

Why use the accusative case in problemi?

The verb çözmek (to solve) takes a direct object. Because the sentence refers to a specific problem ('the problem' rather than 'a problem'), we add the definite accusative suffix -i to the noun problem.

There are no pronouns like sen here. How do we know who is complaining and solving?