Another easy way:
- Go to c:\programdata\sketchup\sketchup 2024\sketchup\materials
- Right click on the materials folder and then click on copy
- Now go to c:\programdata\sketchup\sketchup 2025\sketchup\materials and right click and then click on paste
- Now rename the folder you just passed in to something like Legacy Materials
Now when you are in SketchUp 2025 and you go to the Materials Tray you can click on the Dow arrow and select the Legacy Materials folder and you will see the list of folders from your older version of SketchUp
Hope this helps you. 