Differentiating major and minor characters

Don't overthink it. The definitions are pretty basic. If it helps, think in terms of a TV show:

The Star: That's your Main Character. He's the one tasked with solving the core problem of the story. Essentially, the story is about him doing something.

Special Guest Star: That's your villian. He's trying to thwart the Main Character. But the story is still going to be the main character's.

The Costars: Important characters to the story, but the story isn't about them resolving the problem--they help the main character resolve the problem.

Guest Cast: These are the minor characters who come into the story. They may come in for two or three scenes for a specific purpose, then disappear. Like coroner in a police show who explains how the victim died to the main character. Her role is done after that because she's not needed any more.

One helpful way to manage the minor characters is try to think of where else they can be useful. As an example, you add a doorman to tell your main character about something he saw. The existance of that character is provide information. But what else can you do with him? Maybe you develop a couple more scenes with a bit of his personal life, and then have the bad guy kill him off. If you think in terms of what else a character can do in the story, it helps cut down on the number of characters.

Don't think in major/minor. There's a reason they are called stars; think of a universe. The sun, planets circling the sun, moons circling the planets. All "well rounded" but some far more visible than others.

I write in multiple 3rd limited.

I have a distinct protagonist and antagonist. Then I have a few main characters who also get their own POV scenes, because they help move the plot forward, and create strong conflict.

Then I have a few secondary characters. These are more important than minors or extras, but they don't get POVs. I develop them but don't convey all such development to the narrative, but rather use as much exposition as needed to complement my MCs.

And then of course there are the minor characters. Some people like to use them 'props', I don't personally, but in any case they are the characters that give life to your surroundings (unless your story takes place in a ghost town. )

Hope this helps a bit.

I wouldn't worry that you have too many major characters as long as the following two things hold true:

1 :: The reader can keep everyone straight, preferably without a cast list in the back.

2 :: The story moves at a good pace. (Assuming you're writing genre fiction, of course.)

There's no one way to tell a story. It sounds like this software is making you worry about something you don't need to worry about.

Cheers.

No idea what you are using the software for but it seems it's pushing you in the wrong direction and making you concentrate upon trivia.

What is the software supposed to do?