The pop star joined forces with Mark Ronson and Diplo on the disco-pop banger and has spilled that the chorus became just the middle-eight and she's pleased with how it turned out.
Speaking to Capital Dance, Ellie said: "The chorus is not the chorus on the original. So the original goes, 'If you could see me now. I've got a feeling...' That was definitely in the wrong key … but that was the chorus and now it's just the middle-eight ... but they switched it around and I was quite happy with it."
Meanwhile, the 'On My Mind' singer released her latest album, 'Brightest Blue', last summer and explained the title is inspired by her belief she can "prosper in sadder times".
She said: "Blue is quite a joyful colour considering it's associated with being depressed and down in the dumps.
"There definitely is a melancholy tone to the album with the lyrics and it's certainly not like, 'Let's all forget our problems.'
"It's kind of my way of having this illumination that felt like I could prosper in the sadder times. That's what I've always managed to do - to get myself out of those sad times by writing and by getting my feelings out."
The record marked the 'Love Me Like You Do' hitmaker's first in five years and she admitted she didn't feel "emotionally equipped" to make an album in that time.
She said: "There definitely were certain things that set me back. I felt like I was in a place where the songs were not reaching, they weren't strong enough in my opinion.
"So I waited until I was properly ready and emotionally equipped.
"I also had technical stuff, like a change of management, I moved back to London and I got married. So lots of things happened in that time and it's only really now that I feel like I'm completely ready to embrace that life again."