I'm new to Krita, and have been getting the hang of navigating the program for a couple of weeks now. I've created 10 or so custom brushes to suit my art needs. Today after loading up the program, I've found that all of my custom brushes are no longer in my brush history and I can't find them anywhere.

I have to say, I came from Sketchbook and they wiped my custom brushes every time they updated, which was damn near every other week. Please tell me this isn't the case with Krita and that they are hidden somewhere in the interface?

Also, if there's a way to set my customs in a docker on their own (Like Brush Presets instead of Brush History) that would be very helpful.

Edit: If you're wondering why I can't remake the brushes, none of the new ones I'm trying to create will save, as they automatically reset upon exiting the Brush Editor.

Which version of krita and which operating system are you using? Are you using an installed package or a portable .zip or appimage?

I get the impression that everything was working fine, including your custom/personal brush presets, on a session by session and day by day basis and then, one day recently, things suddenly went wrong as you described. Is that what happened? (It's not supposed to happen.)

If so, can you think of anything you may have done that could have caused this? (Updating krita, installing anti-virus software, anything.)

When you made them, did you do 'Save New Brush Preset' in the brush editor (giving them unique names) or did you use 'Overwrite Brush'?
Can you find them in the Brush Presets docker when 'All' is selected at the top of the docker?

You can't have a personal docker for your own brush presets but you can put them onto the popup palette (right-click the canvas) by giving them a particular tag and then selecting that tag to be used in the popup palette. The popup palette can display up to 30 brush presets of a particular tag.
You can also filter the brush presets docker by tag (at the top) or by name (at the bottom).

When you try to remake the brushes, do you use exactly the same method/process as when you first did it or are you trying a variation of some kind?

In case you aren't aware of it, the manual is here: https://docs.krita.org/en/