Please rename the 8.0 folder noted here:
Mac: /Users/*your-user-name*/Library/Application Support/Autodesk/SketchBook
Win: C:\Users\YOUR-USERNAME\AppData\Roaming\Autodesk\SketchBook
When you re-launch SketchBook, a new 8.0 folder will be created and you can hopefully set your preferences via SketchBook > Preferences (MAC) or Edit > Preferences (WIN)
https://help.autodesk.com/view/SKETPRO/ENU/?guid=SKETPRO_Help_sb_basics_back_files_settings_html
David Lau