B Permit: Moving Canton or Job

[Dogope]

I am a British citizen with a B permit before Brexit from Freiburg. I was in full time employment when I got the permit however, now I only work part time earning around 1,500. I am still self sufficient and can afford the small apartment, insurance and food without needing help.

I want to move to canton Bern but I do not know if I am allowed, if they will just change the address or redo the permit.

If they redo the permit, I am unsure if I will get a new one either because I do not earn enough or because I am British (even though I should have acquired freedom of movement rights, I think).

Would someone be able to clarify my situation to me please?

On a side note to this, am I allowed to leave my job on a B permit for another one without any need to notify the canton?