How to assign a permanent drive letter to a USB drive on Windows
This tutorial will show you step by step how to assign a permanent (also called persistent or static) drive letter to an external hard drive or USB flash drive in Windows 10 and 11.
We'll be using a tool that's already built-into Microsoft Windows 10 and 11.
How to assign a permanent drive letter to a USB drive in Windows 10 and 11
1. Insert the USB drive from which you want to change the drive letter into your PC.
2. Right-click on the start menu button.
3. Click on Disk Management.

You can also open Disk Management by typing disk management or create and format in the Windows search bar and then click on Create and format hard disk partitions when it appears.

4. Right-click on the USB drive from which you want to change the drive letter.
5. Click on Change Drive Letter and Paths.

6. In the next window, you click on the Change button.

Note: If the Change button isn't working and greyed-out, you will have to click on the USB drive to select it.

7. In the next window, you click on the selection menu button and select a letter from M to Z. The letters M to Z are almost never used on most Windows systems.
8. When you're done selecting a drive letter, you click on the OK button.

9. When the “Some programs that rely on drive letters might not run correctly” warning appears, you click on Yes to continue.

Windows will now assign the selected drive letter to the USB drive.
10. You can now close Disk Management.
Related:
How to change the drive letter of a USB drive in Windows 10 & 11