In case you are still confused about the new v5 login system, I'm going to walk you through it, and hopefully clear up some of the confusion.
First, when you go to the beta board, click on Log in. You will see this screen:
Sign in as one of your characters first, using your current username:
The first time you log in, you will be asked to create a new global account using your e-mail address. (I can't show you that screen because I have already done this and it won't give me that screen again.) You will also be asked to "upgrade your account." You should also do this, but be forewarned: You will be sent an activation key to your e-mail address, so be prepared to check your e-mail. (I am going to look into whether the activation key e-mail can be skipped, but for now, you'll have to do this.)
Now, let's say you're logged in, but want to link another account to this one. You could log out and back in as that character, again using the character's username. It will then ask you to sign i by your e-mail address. It will then take you to this screen, where you will enter your e-mail address and password for your global account:
Now you have two accounts linked together. This will allow you to switch between characters with just a couple of clicks.
Let's go through that again. Let's say you sign in with your e-mail address:
If you have a few accounts linked together, the next screen will look like this. If, say, I wanted to log in as Natalie, I would simply click on her icon, and I would automatically be logged in as her. But let's say I wanted to link another account. I would click the "Link another forum account" link, that the arrow is pointing to:
The next screen, then, would look like this:
And after I enter in the username and password, I simply click Continue, and the next screen will look like this:
Click Continue again, and you're logged in. (Yes, this image *should* say Welcome Dawn Meade, not Welcome Natalie St. Clare. Oh, well, you get the idea. I'm logged in now.) But what if I want to switch accounts again, and don't want to log out? Well, you don't have to! See the box at the bottom with the circle and arrow I added?
Let's take a closer look at that box. It has three tiny icons on it. One that looks like two people, one that looks like two boards, and one that looks like a little gear:
Clicking the one with the two people will take you back to this screen:
Click on the character of your choice, and you're logged in as that character. You can also, of course, create a new account, or link another account. You NEVER need to log out with this system... click Remember Me when you log in, and just link all of your accounts to this one, and in the future, you will be able to switch accounts with just two clicks.
Clicking the second icon will take you to this screen. If I had other accounts on v5-upgraded boards, they would be listed below the ones for UTNG. Since I don't, you'll just have to imagine it. Sorry.
The third icon takes you to a screen like this, where you can make changes to your global account. For example, I chose to change the fact that Arthur Weasley's gender was female. Oops.
I hope this helps and that I haven't confused you more. Just try it a few times, and I think eventually you will like the idea, even if it does take a little while to get it all set up. Once you are set up, it really will be easier.