Amanda Bynes’s parents are deeply concerned that their daughter may hurt herself or others unless they are allowed to assume control over her medical care and finances, court filings show. The petition Richard and Lynn Bynes filed Friday not only details her public incidents of disturbing behavior, including several arrests, but also reveals that Bynes, 27, has stated fears that she is being watched by smoke detectors and other devices. Ventura County Superior Court Judge Glen M. Reiser delayed ruling on the conservatorship petition, stating that there was no rush to act because the actress is under a two-week psychiatric hold. Reiser scheduled a hearing Aug. 9. ‘‘We are deeply concerned that Amanda poses a substantial risk to herself, to others, and to property based on recent events in her life,’’ the filing from Bynes’s parents states. It cites her bizarre behavior in the past year. Bynes was put under the psychiatric hold Monday after authorities said she set a fire on the driveway of a home in Thousand Oaks, Calif., where she grew up.