Custom difficulty proficiency bonus

[Onetel2]

Hi, new to the game and to this genre in general.

Under custom campaign i noticed you can modify the Proficiency Bonus, from -1 to +4.

I know that a character like the Warlock will get a +2 in Charisma for, well, being a warlock. This bonus increases at level 5 and 9 for a total of +4 Charisma by the end of the game.

But what does modifying that rule do?
If I were to put the proficiency bonus to -1, will i start with a -1 and eventuall go up to +1 at level 9?

[Cartesian Duelist]

Here's how proficiency bonuses actually work:
https://roll20.net/compendium/dnd5e/Character%20Advancement#content

[Recjawjind]

Proficiency bonus doesn't apply to your ability scores, it applies to things you are proficient in.
If you set it to -1, you would start with a proficiency bonus of 1, because usually the bonus from level 1-4 is 2. Then it becomes 2, because usually the bonus from 5-8 is 3, then 3 from 9-12 because usually its 4.