There is a bulk edit - pleased to share it as it took hours and hours to find it - good job I was in the garden as the laptop would have gone out of the window long before I solved it.
Got to active listings - if you go across the line of tabs immediately above listing the 'offers' tab will show you if you have activated offers and you can get the list, but you have edit individually.
To bulk edit, go the the top row of tabs - overview, orders, listings etc. Go to marketing and on the drop down go to offers new - this brings you to the list of offers.
On the right hand side go to all offers, the drop down gives a choice, all, automated, not automated.
Now you can go into each offer and edit both automated offers and counter offers blue circles. Here is where the end date is also shown.
I edited the 60 odd remaining in ten minutes! But even ten minutes to reverse something I didn't want or ask for is not on. Much less the very long time it took to figure it all out.
Did you know that, if you send out offers, while those offers are 'live' for want of a better word, if another buyer puts the item onto their watch list, there is no notification to send them an offer. Spent a fair bit of time figuring that out today. Also, although eBay state in their help pages that the offer lasts for 24 hours, they seem to be locking the listings, so that it can't be changed- for many days! Which suggests that the listing is out of bounds for outgoing offers for some time.
