Section 4523 Of Chapter 2. Jurisdiction And Venue From California Probate Code >> Division 4.5. >> Part 4. >> Chapter 2.

. The proper county for commencement of a proceeding under this division shall be determined in the following order of priority:
  (a) The county in which the principal resides.
  (b) The county in which the attorney-in-fact resides.
  (c) A county in which property subject to the power of attorney is located.
  (d) Any other county that is in the principal's best interest.