Quit the application.
In Finder hold down the option/alt key while selecting the Go menu item. Select Library. Then go to Preferences/com.apple.Safari.plist. Move the .plist to your desktop.Open the application and test. If it works okay, delete the plist from the desktop.
If the application is the same, return the .plist to where you got it from, overwriting the newer ones.
If you want to make your user library permanently visible, run the below command in Applications/Terminal.
chflags nohidden ~/Library/
You will need to do that after any updates.