Last week, Microsoft released the first Creators Update preview for the Xbox One and at the same time, finally opened up the Insider Program to system updates. Four separate tiers were created, the top three of which are invitation-only.
The most active Insiders get to be in the Preview Alpha ring, which is the one that got the Creators Update preview. When Microsoft selected the Insiders that were eligible, it chose which console would be the one on the Alpha ring, not selecting the one that's used most frequently. Naturally, Insiders that have multiple consoles would have preferred to be able to choose which one is in Alpha themselves.
That's now changing. Due to feedback, Microsoft has decided to allow Insiders that have been selected for the Preview Alpha to choose which consoles are enrolled in it.
Remember, while you can activate up to ten consoles, if Microsoft finds that you're inactive, it can remove you from the Alpha ring. Also, keep in mind that once moving to a new ring, it can take up to 72 hours to actually happen.