Security issues

A local device not a member of my household is connecting to my devices & changing my Apple ID passwords and accessing apps ie music & spy ware applications which copy my data stored on iCloud to access’s passwords. I can’t keep passwords longer than12 hours. I have had my devices reset to factory settings but as soon as I connect up to a WiFi or sim card it begins again. I have learned that data stored on iCloud is placed in his tag colour. Siri is programmed at start up to augment changes to facilitate his access to remote keyboard. My phone iPads are not allowed to sleep and I can only switch of my WiFi disconnect my SIM card & try to place my device more difficult to access ie a safe or under a mattress please can someone help. Apple stores can only reset to factory settings but hours after my devices go into reverse. I believe we are being stalked as we do no longer trust our devices with financial data.