Backup Save Location

Is it possible to change this? Doing my head in having all these “Backup of…” files lying around

Are they called “Backup of…”?
In General, if you open a file and if set in the Preferences, SketchUp creates a backup file upon opening a file in the same directory as were the file resides.
In Windows, it will get a .SKB extension, on Mac, a tilde (~) is added to the original file’s name just before the extension.
I believe you’re on a Mac. You can have an Automator workflow set up that moves the backup files to a specific folder, or untick the feature in SketchUp->Preferences->General

I had an Automator workflow to create consistent folder setup for Projects, these are real time savers

Edit: I did not noticed it was in the LayOut category
LayOut backup files are called:
“Backup of … .layout”
On both Programs the preceding applies.