No. Unless you are exempt, you have a potential remedy under the federal Fair Labor Standards Act. Here is a link to the Department of Labor website for additional information:
This response is merely a general discussion of an issue based on the information provided. It is not intended as legal advice and does not form an attorney-client relationship. You are encouraged to seek out an attorney of your choosing in your local jurisdiction, and to discuss your legal issue with that attorney.
No. This is a violation of the Fair Labor Standards Act. Your employer has a duty to pay you for overtime if you are non-exempt under the statute. Also, your employer has a duty to maintain accurate time records. If your employer is changing the time records, you should keep your own separate set of records.
If the employer is violationt the Act, it may be liable for double damages plus attorneys fees. You should likely contact an attorney to write to the employer prior to having to file suit under the FLSA.