I'm having trouble conjugating "matter" here:

"Somehow, in our workplaces, we have collectively forgotten that how we talk to one another, how we resolve misunderstandings, and how we work through our differences matters."

Or, should it be "Somehow, in our workplaces, we have collectively forgotten that how we talk to one another, how we resolve misunderstandings, and how we work through our differences matter." ?

Any assistance with the proper rules of grammar here would be appreciated. Thank you.