" It the soil ph WAY too low? "

Unlikely. Hydrangeas prefer an acidic soil but the soil pH is also what contributes to the flower color. Low soil pH releases available aluminum and that's what makes hydrangeas blue instead of pink or purple. Any white you might see is either specific to the cultivar or just an early stage in the flower coloring.

It sounds like the blooms are color changing. Can you post pictures (do you have before-after pics... that would be better? ;o)) The soil pH would not have much impact yet as the roots tend to be still growing on the potting mix that the shrub was sold with. Blues tend to fade to lighter/faded shades of blues or even to a grayish white but not normally to a pure white.

I updated the post with some pictures

Hydrangeas of that size in full bloom in early May have been forced in a greenhouse by the growers via chemicals and day length manipulation to bloom early, heavily and to a specific color. Once planted in real soil (not potting soil), they rapidly lose whatever effect the growers intended (and are no longer applying) and will resort to their genetic coloring as influenced by the native soil pH.

But why are they leaves turning white?

I do not see any white leaves. But it is possible that these plants are receiving too much sun and the leaves are bleaching out as a reaction to that.