If you go to Korea, you're gonna hear that a lot more. The 요 ending often sounds like 여, (same for 오/어 here) because it's easier to pronounce when speaking at a normal pace. It's not much of a problem with the audio as it is a feature of the language, so don't worry, you won't remember it incorrectly (you might spell it wrong though).
For another example, listen to this: 안녕히 계십시오
In English, you would have a comma after "please" in your sentence. It would be like you'd already asked for someone to focus, but they weren't doing it enough, so you're asking them to do it more. It's not a natural sentence overall though. The sentence they gave is more natural, and is as if it's the first time you're asking the person to focus.
"please pay more attention" wrong but answer is "please pay attention more." In English there is a subtle difference. The first addresses the amount of attention being paid where the second addresses how often attention is being paid. I would have thought the first is more appropriate for the translation but I must be wrong......just wondering what everyone else thought about this one.
That's not natural English. Your sentence would have to be: "Please be more focused." You just needed to leave out the "be" and change your word order to "please focus more." Focus = in progress/something you are doing or something someone wants you to do right now. To-be-focused = is more of a state of being.