

Do that by right-clicking an empty space on the Taskbar and selecting Task Manager, then look for the 'Skype' process in the Processes tab (if you're not seeing a Processes tab, it means that Task Manager is showing a simplified view - click on 'More details', bottom-left corner to switch to an advanced view).

Make sure the app is no longer running in the background by looking for (and ending if necessary) any 'Skype' process in Task Manager. If Skype is opened, right-click its icon in the bottom-right notification area (or System tray area) and select 'Quit Skype'. The solution that worked for me was to manually reset Skype's settings. After Microsoft rolled out a few Skype updates that did not fixed this problem for me, I tried to uninstall and re-install Skype but with no luck, still. In this quick article, I'll show you how I fixed this problem. It basically did not stay signed in, even with the option 'Automatically start Skype' being enabled in Skype's General Settings.

Basically, I saw that even if I'm logged in on Skype, without signing out in the app, after I restarted the PC, Skype was prompting me to enter credentials again, each time. After fixing an Windows 10 stuck on updates, I noticed that the latest version of Skype for desktop was failing to sign me in automatically after each Windows restart.
