My Head to Head you can set lineups for each day, the site is glitched out...if you keep hitting refresh or switching between days over and over...eventually the Submit tab will will kind of free up..so you can change rosters..the yahoo site is a piece of #$%$..worst I've ever used in fantasy, stats just change randomly or reset to zero mid day... I Won't ever use Yahoo again after this unless these glitches get fixed soon. For roster changes its quicker and easier, (If you have a smartphone) to use the yahoo fantasy hockey app....click on the pencil in the upper corner...cuz naturally when I think of edit rosters..I think pencil icons!
I'm in a league where all of the rosters are different then what everyone originally drafted. The only thing I can think of is the commish changed the settings in the league or their is some glich in Yahoo.
Wish I could answer the question.