Visit the Paternal Line page and confirm the new haplogroup setting
For now it only works for father/child relationships, and is not supported for other male relatives such as brothers and uncles.
In the meantime, if you are sharing with a male paternal relative (brother, paternal uncle or nephew, paternal male cousin, paternal half-brother), you will see his name and paternal haplogroup listed on the right-hand side of the Paternal Line page under Your Family and Friends. You can click on your shared paternal line to learn more about it. You can also add your paternal haplogroup to your profile in the "About Me" section.