Why does my play/pause button my headphones affects youtube?

I use my computer a lot to listen to music and watch youtube. Very recently I've noticed that pressing the play/pause button on my headphones will affect youtube rather than spotify if that's what I used more recently. It never did this before and it's very annoying, is there anyway I can turn that off?... show more I use my computer a lot to listen to music and watch youtube. Very recently I've noticed that pressing the play/pause button on my headphones will affect youtube rather than spotify if that's what I used more recently. It never did this before and it's very annoying, is there anyway I can turn that off? It's only been happening for a day or two and I haven't changed any settings or anything.
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