Hi, 

You can visit our Hydrangea pages for pruning tips and general problems : https://extension.umd.edu/resources/yard-garden/shrubs/hydrangea/

Not much that can be done about leaf spot diseases, which you are seeing on some of these leaves from last year. Leaf spot diseases are weather-dependent but also likely influenced by cultivar susceptibility. Thinning those stems a bit could help by improving air circulation among the foliage later this season, especially with the older dead stems towards the bottom.

Don't trim until after they are done blooming, or be prepared for reduced flowering this year as a trade-off for long-term health improvements.

We suspect the shrubs aren't getting much sun or are being watered irregularly. Maybe it is too often- does a sprinkler get those leaves wet routinely?

A soil test might reveal a nutrient deficiency or pH (soil acidity) issue, though with flowers that blue, I suppose it's likely not too alkaline. Blue flowers tend to need more acidic soil or a lower pH and the pinkish and purple flowers tend to need more basic soil or a higher pH. The foliage looks a little nutrient-deprived, though, but it could look like that from over-watering too, so a soil test would be helpful to guide rehabbing these. 

Let us know if you have further questions on care. 

Emily