Python Script malfunction

I have several scripts in Python code. The earliest one was using Python 3.5. I foolishly allowed a version 3.10 update recently. It has now created a problem with all scripts. To start, they run very slowly (scrape). As expected, some returned data that makes no sense. I use windows 10 and have completely scrubbed my standby machine (with DBAN) and reloaded windows ready for the new installations. My next step is to setup Python on the clean machine in a process that will enable a couple of versions of Python to run. That will mean I need to direct each script to the version it will need. My earliest script has the hash command (#!/usr/bin/python3.5) but on reading up on windows commands for Python in windows, this does not appear to be the right command for windows to enable the script to direct to the correct version . My job: to outline the whole process of installation and outline the correct code to seek out the right version of python for each script. I may also need to re-load the correct libraries but that will be something to determine once it is up and running.