Can Quicken PLEASE bring back feature to "Edit This Instance" for a scheduled transaction?

A scheduled transaction is basically a template for future transactions. Quicken Mac has the ability to edit some fields in the next instance only: the date and or the amount. Even this limited editing capability causes confusion for some users, who don't grasp the difference between editing the next instance of the transaction and editing all instances of a transaction. (You mention an "Edit Instance" in the drop-down menu, but I think you are referring to "Edit All instances".)

I believe the Quicken Mac product manager at ne time said they had looked at allowing users to edit other fields of the next instance of a scheduled transaction, but couldn't implement it because Quicken Windows doesn't have that capability, and the Mac and Windows programs both need to work equally with the mobile app/web interface 

So to clarify what @NotACPA wrote: why not just click on the next instance of the transaction in the register, and click Paid or Deposited. This "posts" the transaction — turning it from a templated future transaction into a real transaction. It's still in the future, so it doesn't affect your account balance today; it just separates this next instance from the scheduled template so you can edit anything you want about it: the date, memo, tag, amount, splits, etc. In your case, however, this would be problematic, because you've said this transaction might remain unpaid past its scheduled date.

The solution I can think of here would be to edit the date to push it a week or more into the future. This would keep it as an upcoming transaction. Of course, you'd need to keep bumping it forward as long as it remains unpaid. You might want to use an additional column to insure that a transaction doesn't slip into the past as if it had been paid when it actually wasn't. You could use the Action column for this: when you mark the scheduled transaction as Paid so you can edit it, add something like "UNPAID" to the action column. That would make it easy to spot if an unpaid transaction had crossed the Today line from future to past, so you could bump the date into the future. Alternatively, if you don't currently use the Status column to flag transactions for review, you could use this column and the Flag For Review status (Control-Click the transaction and select Set Status of Selected Transaction To > Flag for Review) as a marker for unpaid transactions.