OK, techie querie:
I created a sheet, transfered ownership to someone else (another licensed user), who then gave me admin permission as part of a group of which I am a member.
However, I can't insert columns - the option is greyed out. This only happens with one sheet, other sheets that seem to have the same history and set-up will let me insert columns.
The current sheet owner is on holiday, so this causes a bit of a problem:
a) I don't understand why I can't insert columns if I have admin permission.
b) It would be useful to have some kind of "ownership override" as the main Smartsheet account holder.