Titus 2 Paul wants Titus to teach sound doctrine, the Grace and Glory of Christ, and this leads to transformed people, affecting how we relate to one another.
Titus 1:5–16 Paul wants the church’s in Crete to remain faithful, so instructs Titus to appoint Godly elders, emphasising that good doctrine produces a Godly and gospel focussed church.
Titus 1:1–4 Paul wants the essentials, the foundations, to sink in and be firmed up, which means not departing from his teaching, but instead clinging to the true Gospel, and for this to produce changed lives.