The two-time Grammy nominee previously teased SUBJECT TO CHANGE during a chat with PEOPLE in April, and said that the '90s-tinged "Heartfirst" set the tone for what's to come. "There is a lot of nostalgia to this record," she said. "It does sound really '90s-inspired, '90s country and '90s pop... I really just wanted to start this next chapter with something that feels good. It's breezy, it's happy, and I hope people hear that."