Hello,
Thank you for writing to Microsoft Community Forums.
In which format are you trying arrange the PDF files?
By default, File explorer will sort the files and folders in alphabetical order. You can also select other sorting options to arrange your files. I suggest you to try the following steps mentioned below and check if that helps:
1. Open File Explorer.
2. Click on View.
3. Now click on the Sort by drop down.
4. Select the option that best suits your needs.
Note: All the files or folder in File Explorer will be sorted in the format that you have selected. This option will remain until it is changed manually.
Hope it helps.
Sandeep Kumar M
Microsoft Community – Moderator