Hi Cat lady. I'm Greg, 10 years awarded Windows MVP, specializing in Installation, Performance, Troubleshooting and Activation, here to help you.
You said you're using Windows Scan, the simple scanning app that comes from the MS Store app. Correct? During a scan if you open it and look under File Type, the drop down includes .pdf file type to choose to save the file to.
It's illustrated in Step 5 here with the PDF setting already set:
https://www.windowscentral.com/how-scan-documen...
If you'd rather use your scanner software, chances are it only needs to be reinstalled after an Upgrade. Go to the scanner or printer's Support Downloads webpage to download and install the full software package (which you may have to dig to find as they're pushing thinly developed apps from manufacturer, too). In rare cases you may need to uninstall the software in Apps Settings first before installing it fresh.
If it won't install then try again in Compatibility Mode:
https://www.groovypost.com/howto/run-old-softwa...
https://social.technet.microsoft.com/Forums/win...
I hope it helps. Based on the results you post back I may have other suggestions if necessary.
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