Hi stephenlyon2,
I'm Paul and I'm here to help you with your concern.
Your passwords are stored on the Microsoft servers (Cloud) under your account. This allows your passwords to be synced across all of your devices once you have signed into the browser on your device. These passwords are then cached onto the local folder for Edge under AppData(C:\Users\"Username"\AppData\Local\Microsoft\Edge\User Data).
You can get additional information provided by Nathan Roberts (SunkNath) from the link below.
https://answers.microsoft.com/en-us/microsofted...
I hope this helps. Feel free to ask back any questions and keep me posted.