@Irene316 You don't get to pick your own number and it seems like a non-issue in my opinion. This forum is the only place those numbers appear.
The numbers got assigned a year or two ago in order to make it possible to tag other users when posting.
When you go to tag someone, so they get a notification that someone has responded to them, as soon as you type the @, a box with only 5 posters in that thread appears. But there might be 15 posters in that thread and the one you're looking for isn't there. So if you start typing in the desired poster's name and number in, that will then appear in a new pop-up box for you to click on.
As there are probably 315 other Irenes who have posted here over the years, just typing in Irene wouldn't work. That's how and why there are numbers after our names.