I would do what you are doing...
C drive for Windows and all software
J drive for your video files
K drive for projects and temporary files
Edit Menu/Preferences/Scratch Disks path sets should stay as your direct them.
However, I have found that Edit Menu/Preferences/Media and that Media Cache Database will regenerate to the default location as shown there.
The ease with which a project and its assets can be deleted is also a consideration in setting up Scratch Disks.
At the default level, files and folders from different projects for a version will end up in the same folder where you need to sort
through files/folders names to get at the file folders you need to delete to get the project off your computer.
You can set the Scratch Disks to "Same As Project" with regard to location. Whereas, Edit Menu/Preferences/Scratch Disks define
the path of the automatically generated project's assets, it is the new project dialog that defines the Save In location of the project.
After the fact, you should be able to use File Menu/Save As to change the location of the project.
All that being said...you can explore
a. pointing the Scratch Disk to Same As Project after you point the project to K
b. set up for separate folders for each project for your version and direct each project to its own folder...then point the Scratch Disk for the project
to Same As Project.
Please let us know if any of the above worked for you. If you have questions or need clarification, please do not hesitate to ask.
That's great! I set up all the scratch discs to "same as project". Then I open PE13, then New Project and point to a folder I have already created using the file manager and then save the project right away in the right place. This seems to do what is required - must say its not obvious?? (or maybe I am thick). I have a long history of PE4, PE7 and PE10 and PE10 seemed somewhat less "clunky". But so far so good.
Thanks for such a prompt response.
Great news that the suggestions worked for you.
The "...so far so good." sounded great.