change folder path for undo.ac$ file

[Dario955i]

Hi, I've changed all temp folders set in the main option tab, but file undo.ac$ is still in the defult user folder
(...AppData\Local\Temp)

As in the operation I'm doing undo file is getting too big, I need to move it in another folder. Any suggestion?

thank you in advance

[j.palmeL29YX]

The path for this files is stored in the System Variable TEMPPREFIX. 

But this variable is set to read only - you can not change it.