I think only moderators can give you a satisfactory answer to those questions asked.
I will also summon @dragononcrypto how to get the Custom Title step by step.
There is no step by step guide to be granted a custom title. It's something that is awarded, not a title that is applied for per say. It was otherwise explained on previous page that only realistically
paying for one is how you can guarantee receiving it. You also don't need to summon, other users are more than capable of providing you the answers you seek as they have already done so.
What you said could be true because I saw that members with Custom Title "Shillers" cannot be changed.
I saw it on the profile of Gengentrader members, which did not have Custom Title written, maybe that means the word "Shillers" was also not changed.
It could also be a punishment because the post he had was not good or violated the forum rules so that his "Shillers" was a punishment and the Custom Title "Shillers" could not be changed unless he paid the fine that had been made by the Admin.
Not that anyone appears to be able to recognize or understand the difference, but I'll try anyway: Shillers is
not a custom title, it's a memerbgroup. It can be applied as the
default membergroup - thus appearing on profiles under the name,
similar to how custom titles appear -, or otherwise as an additional membergroup, thus only showing the badge on profiles. But regardless, a default membergroup is still not a custom title, it's just the membergroup name being applied.
This is precisely why for Mia Chloe the title is shown as a custom title on profile, and for the shiller it is not shown as a custom title, because it's not a custom title.