More Windows 10: Reset the Screenshots Counter

Open Registry Editor by pressing the Windows key plus 'R' to open the 'Run' box, then type in 'Regedit.exe' and press 'OK'. Then, in Registry Editor, navigate to HKCU (Current User)\Software\Microsoft\Windows\Current Version\Explorer in the left-hand pane. Then, in the right-hand pane (the 'values pane') look for the following DWORD: ScreenshotIndex, and right-click on it....

Choose 'Modify' and in the little 'values' window that opens, change its value to read '01' (no quotes!)....

  ....then click on the 'OK' down at the bottom of that little editing window, and close Registry Editor. Your numbering sequence for screenshots is now reset to one again.