To make it quick and easy to associate a user to an asset without having to edit the asset, then search them up, etc. can there be an asset option which is called Associate Asset to User as per the mock-up below.

The popup screen should automatically populate the Used By relation with the Last User value on the asset by default but you can make alterations as needed (e.g. add notes, dates, or change the user) in the popup window before clicking the Add button. Once you've clicked Add this change is saved to the asset and the screen refreshes.
This would make organising the system a lot easier than having to "edit asset" each time and find the user who is commonly using a specific computer. I know you can also update the assets in bulk and via the API potentially but this is good for ad-hoc assignments from within the UI itself without leaving Lansweeper.