Locked in seat, one-arm press, zero cheat.
Keep your back pinned and don't lean away from the working arm to muscle it up.
Pressing one dumbbell overhead from a supported seat makes a single shoulder carry the whole load while your torso fights the urge to lean away from it. That offset is the feature, each delt works alone with its triceps finishing the lockout, so a dominant side cannot paper over a weak one. The back pad keeps it strict, which is exactly what one-arm pressing needs.
Almost everyone has one shoulder stronger than the other, and two-dumbbell pressing lets the strong side set the pace. One-arm work exposes the gap and lets you match reps and load per side until it closes.
The offset load is pulling you toward the weight, and leaning away is your body cheating for leverage. Brace hard, keep both hips and shoulders square against the pad, and lighten the dumbbell until you can press without tilting.
Yes, press the weaker side first while you are fresh, then match those reps with the stronger arm. It stops the gap from widening and gives the lagging shoulder the best quality work of the session.
