What is the right/proper or advisable way on upgrading? Should I uninstall first the previous version before installing the latest version or the other way which is installing the latest version without uninstalling the previous one?
Just download the installer and run it. There is no need to uninstall previous versions; the new version will overwrite the old one. No data will be lost and you will not need to redownload the blockchain. As usual, you should backup your wallet file just in case, but there shouldn't be anything that effects that.Sorry but I don't know how to locate the log files.
All of Bitcoin Core's data (including log files) are at %appdata%/Bitcoin. Type that into the bar for the file explorer and it will take you to the datadir. The debug.log file is the file that we need to see.You can also get the debug.log file by going to Help >Debug Window. In the main Info tab, there is a button that will let you open the debug.log file too. It also gives you the full path to the datadir.
