Air carrier Captain reported a cabin altitude warning indication. Crew referenced QRC and returned to the departure airport.

Narrative

Climbing through 12;000 we got a cabin altitude warning indication. I immediately leveled off the aircraft from the climb and looked up at the bleed air panel. All indications looked normal with engine bleed air on both engines and both packs were in auto. I asked the FO (First Officer) to talk to ATC and request priority handling and immediately began a descent to below 10;000. ATC cleared us to 9;000 feet and we began referencing the QRC for the immediate action items. ATC asked us our intentions and we both agreed on a return to ZZZ. The FO asked about donning the oxygen masks but by the time we got to that point we were already below 10;000 feet. On the initial climb passing 10;000 I referenced the cabin pressure control but I do not remember verbalizing what it was. We ran the QRC and continued to the expanded procedures. At this point I took the radios and continued flying while the FO continued on with the checklist. When the step came to checking the pressure controller to see if it was in auto or manual; it was in manual. The FO said that he had put it in manual mode during the procedure. At this point he asked me if I would like to continue with the checklist but we were at the conclusion. We got vectors back for the ILS XXL into ZZZ and made an uneventful overweight landing and taxied back to gate.