I like that there is a note option on cleared transactions in Quicken Online. But why is there no "notes" option when adding upcoming bills (one-time or otherwise). I like to add confirmation numbers in that field for unreconciled transactions.
I just checked with the lead engineer on that feature and my advice to add note info to the Payee field was bad advice.
The problem is that once the transaction is matched with your cleared transaction, it will "teach" Quicken Online that the edited payee name is the one you want to be used for all transactions from that payee going forward. You could teach it to use a better payee name the next time you get a transaction from that payee, but that's obviously not the best solution.
So the only workaround we can recommend for now regarding adding notes to upcoming transactions is to put extra text into the Check # field if the upcoming transaction isn't a check. (And this workaround of course will work only in checking accounts -- because they're the only ones that have a Check # field.)
The lack of a notes field is causing me great distress as I make many transactions per day and have difficulty remembering what all of them are for. :-( Sadly, the lack of a notes field for upcoming transactions is tempting me to jump ship for Yodlee or Wesabe.