warthog, if webz's post above is correct you have to finish your edit lineup BEFORE Monday...I was trying to edit mine at 2:15 am this morning and it wouldn't save the changes. I think we're both stuck with our unedited teams this week. dang.
Yes, you need to set your lineups before midnight Sunday night (PST) I could probably go back and find about 5 posts where I mentioned it was a weekly league. All the information is right there in the league settings. Sorry if it didn't work out for you this week, but I'm sure it won't cost your season. Check out this link I found. What is the deadline for making transactions? - Yahoo! Sports Fantasy Basketball