Can I sumbit a motion for change of judge in CA?

You cannot changes judges. If you do not have an attorney, you probably need one so that your side can be accurately presented to the court.

You need to file a motion under CCP 170.1 which will be heard by the presiding judge. They usually deny them and that just exacerbates the problem with the sitting judge.

Generally you have to file that motion within 10 days of the case being assigned to the judge, if you don't then you have to show that the judge is actually prejudiced against you.? That would normally require the judge making comments that show he or she hods some sort of grudge against you, not just that he ruled in her favor.

First and foremost, your motion will likely lose unless you can prove actual prejudice. The easy time to disqualify a judge is before a first ruling, and in reality even earlier than that. However, look up California Code of Civil Procedure section 170.1 for the procedures to have your sitting judge removed for grounds of actual prejudice. Understand that this then goes to another judge to consider the question, and whoever this judge is will probably have done it before and rejected most or all of the previous such motions. This especially applies if the judge hearing the disqualification is from the same court house and you are asking him/her to find their coworker is prejudiced. One additional option applies if your case is not before a judge but a commissioner instead. If the commissioner has not yet heard this particular matter, at the start of the hearing when you state your name also say, "I respectfully do not consent to this matter being heard by a commissioner." Upon doing this, the commissioner still hears the case not as a judge but only as a referee. The commissioner then sends a real judge a written report and recommendation for a ruling. You can submit a writing to the judge as well. The new judge may schedule a hearing or trial, or may rule on the writings alone. However, if you try to navigate this path without an attorney experienced in referee cases in family court, your risk of getting burned is great. Plus, you won't make any friends with the commissioner. If this person is a commissioner and heard the same matter already, such as child support, he may rule you waited too long to object and your participation in the previous hearing(s) was an implied stipulation to a commissioner hearing the matter. Then you are stuck with him AND you pissed him off. OTOH, if he only heard child support previously and then there is a custody matter, that should be seen as something new and requiring a new stipulation.