When upgrading does V4 firstly remove V3- firewall only

At some point I am going to have to bite the bullet and upgrade from V3 to V4 . I am reading various bits and pieces first to try and make sure i don’t make an error.

I have read chirons guide , but for my peace of mind when I open up V4 will it uninstall V3 before it installs V4 ? otherwise will it not be 2 x versions on my computer. As a complete novice when it comes to computers I was hoping that it would automatically do it so less chance of me making a c**k up.

mank thanks