This might be a good point to summarise your circumstances, before this Topic trickles into a second page.
The summary below comprises information you have provided here, combined with information I know of your circumstances from elsewhere back in February, under a different configuration.
- In February, you had a Samsung 24" monitor on the left-hand side as your Primary positioned monitor, with an old HP 19" monitor on the right-hand side
- You had the large number of icons on the right-hand side monitor, and at a satisfactory proximity to the edge of that screen
- You upgraded from Linux Mint 18 Cinnamon to 18.1, and from then on, the right-hand monitor would not present the icons less than 22mm to the edge of screen
- By 30 April, you had retired the HP and had a new Acer, also 24"
- You reversed the orientation of the monitors, and the Acer moved to the left, with the many icons, and your working monitor, the Samsung, moved to the right
- You had presumably reverted to Linux Mint 18, and then 30 April you upgraded to 18.1 and the many icons, now on the Acer, once again failed to present close to the edge of screen, not less than 22mm from the edge.
I hope this is accurate.
Briefly speaking (as I have to go soon), the news I have is not good, depending on your viewpoint and priorities.
Linux Mint 18 shipped with one version of Nemo, which accommodated your desires, and with 18.1 a newer version of Nemo shipped, which did not.
You cannot dial back to the older, satisfactory, version of Nemo, even from a .deb package you can obtain online, because Synaptic Package Manager will block your attempt with a message that a newer version is already in place.
If you remove Nemo, you will cripple your Cinnamon Desktop Environment.
If you try to remove both, you will bork your install, even if you have their replacements on hand and try to do it in the same session.
I have enclosed a screenshot showing a dual monitor setup I have, with the icons closer than 22mm to the screen edge. On the left, a 19" Dell, and on the right, a 23" Acer (incorporated into an All-in-one).
This was done by monkeying with Settings-Desktop, and if you choose to try same, you might let us know what your setting is currently.
Note that I cannot get the icons closer to the edge, where underlying text is larger than the size of the icon.
Other alternatives are that you dial back to LM18, which worked for you, or else try a different Distro/Desktop Environment combination, and subscribe to GitHub and/or Launchpad to see when they fix the current bugs with Nemo.
Regrets that I cannot do better, here is that screenshot