From bottom of right hand column of Page 7 of the Juno DS manual:
Registering a Favorite
1.
Select a patch or performance that you want to
register.
2.
Press the [BANK] button to make it light.
3.
Press a [0]–[9] button to select the bank in which
you want to register the favorite.
4.
Hold down the [FAVORITE] button and press a
[0]–[9] buttons to select the number in which the
favorite will be registered.
Then go to the 2nd item from the top of the left hand column on the next page (Page 8):
"Viewing or Removing a Favorite"
for instructions to remove a single Favorite or clearing an entire bank. If the Juno DS is like my Jupiter-50 and Juno-Gi, the Favorites banks come pre-loaded with "factory suggested" favorites. It is a good idea to go through ALL of these and audit them, before deleting ANY of them, to see if there are any you want to keep. There were quite a few on my 50 and and Gi that I decided to keep. I would delete the ones I obviously did not want, during the audit process, then "resaved" the ones I wanted to keep at the top end of of Favorites memory and deleted them from their original Favorites locations. That way, I had MY Favorites at the low end of Favorites memory and the factory suggested "keepers" at the high end. Any time I wanted to go "shopping" for a "new" set up, I would just go to the high end, see if there was anything I liked, grab it, modify it as necessary, and resave it in lower memory as one of my own.
I recommend downloading the PDF copy of the DS manual, then using the Edit > Find command in Adobe Reader (or whatever PDF reader you use) to search on specific key words. It sure beats "thumbing through the pages".