security being hacked from all sides

I am not a techie but aspire to know at least enough to protect secure my stuff. I have an att modem with wifi and a ZTE cell phone with wifi and I just reloaded your 14.04 with updates ... Please let me know what I should install or otherwise to protect myself from all these hackers. I go on Youtube an have used Chromecast and Gmail with several accounts but right now I am afraid to download any of these. Please help me figure out what to do. I highly suspect my neighbours for several reasons which I won't bore you with. Suffice it to say they have called me to get on, hacked my phone which I can reset if it will help and I think many are using my online capabilities with ubuntu. Can you help me?