I used all 5 home xbox switches

And this is why you abuse the home setting

It's not to be shared with the neighbourhood or.for temporary play if you are over.at a friends play online that way your home switches aren't used

Customer support can’t offer additional switches. If you’ve made five home Xbox switches for the year and need assistance, select Help when you see the message Can’t make this your home Xbox. You may be eligible to receive an exception. If you don't see a survey, you'll have to wait for them to reset on their own.

once your eldest sets your youngest's Xbox as his Home there is no need for him to switch his Home Xbox as his subscriptions and games are linked to his account and he can play them on any Xbox without it being his Home console.

when he tries to set his younger brother's Xbox as his Home it will give an error saying all 5 switches have been used, there should be a Help button/option show up. if he clicks that he may be able to get another Home switch.

I would try to find out why the Home Xbox stops working on your youngest's Xbox.

is you eldest switching it back to his Xbox?

have all 5 switches been used on your youngest's Xbox?

Yes. Multiple accounts can set one console as their Home. Each account can only set one console as their Home though.

As far as I know, if there is a time given for your next switch, you won't see it until after you've used all 5 switches in a year. But if you're using the setting properly, you shouldn't need to use all 5 switches.

You get 5 switches in a 12 month cycle. If you have used all 5 you will have to wait until the 1st switch has reached 1 year.

Xbox Support can unfortunatly not give any more switches if the 5 has been used.

For more information regarding switches of your home xbox you can look in the link provided by the others.