Editing Recurring iCal Events

Does anyone have any idea how I can change a recurring iCal event from timed to all-day? I work every other weekend, and have plotted my weekends off for the foreseeable future. There were some schedule changes, and some of the weekends I was scheduled to work, I am now off, and vice versa. When I went to edit the events, I was reminded they were recurring events, and did I want to change everything or just the one event. I selected once. I am able to change the notation to a day off, but the button that allows me to change the time to all day is grayed out. I have to manually put in 12:00 am as a start and 11:59pm as the end.

Also, my work calendar is shared with my husband. I made the changes on my iPhone, and they migrated to my MacBook. Once my husband came home, all the weekends I had changed were changed back. Is this because his calendar hadn't synced with mine yet, and his changed everything in the shared calendar back? If not, does anyone have an idea why that would have happened? Thanks for your help!