(a) The domicile of every person who is of full age and is laboring under no disability is the place where the family of the person permanently resides, if in this state. If a person has no family or if his family does not reside in this state, the place where the person generally lodges shall be considered his domicile.

(b) The domicile of a person sui juris may be changed by an actual change of residence with the avowed intention of remaining at the new residence. Declaration of an intention to change one's domicile is ineffectual for that purpose until some act is done in execution of the intention.