Switching car insurance companies should not affect your credit or credit score.
I don't switch car insurance that often because I'm mostly happy with my auto insurance company and I've used State Farm auto insurance for 5 years and then later switched over to Progressive Auto Insurance and it hasn't affected my credit score.
When you do get a quote for auto insurance the auto insurance company does pull up your credit but the inquiry the auto insurance companies put on your credit report is a soft inquiry and unlike a hard inquiry the soft inquiry doesn't affect or harm your credit rating at all.
So if you want to shop around for other auto insurance and find cheaper auto insurance then you can do so without harming your credit score.
I only switch auto insurance if I can find cheap enough auto insurance and I also want good customer service which I also get with Progressive auto insurance.
State Farm customer service is great too but I needed cheaper auto insurance so went with Progressive.