Most hydrangeas, particularly bigleaf hydrangeas, will do best in at least a part shade condition. Full sun often promotes that midday wilting you are noticing now. The paniculatas and arborescens tend to be the most sun tolerant and will generally do very well in considerable sun, even in midday, once established.

So ignore those tags! The 'Forever Pink' will need some shade but the PeeGee will tolerate a lot of sun.

PeeGee types are full sun plants, unlike other hydrangeas. They will tolerate partial shade, tolerate being the operative word. I'm not familiar with the "Forever Pink" cultivar. Is it a macrophylla? If so, partial shade is best. I wouldn't recommend planting a macrophylla in full sun unless you are willing to constantly run for the hose.

I have 3 Forever Pinks. Did not winter protect and although the plant is healthy there are no buds hence no flowers this year. If there is a mild spring and no late frost you may get late summer flowers. It's the frost that kills the buds.
Mine gets afternoon sun, 2-3 hours.

Sue

I have an established Forever Pink in full sun. It has lots of big, beautiful blooms this year. Didn't do squat last summer.
Yes, it does wilt midday, but I just turn on the drip hose. Problem solved. :)