Encrypting now Unencrypted Firefox and Unresponsive Scripts

I'm trying to resolve a lot of issues w/my computer & have gotten partway thru my list.  Now I've got to resolve the subject issues.  Every time I open my Firefox, Yahoo, FaceBook, et al. programs, I get message notifying me that I'm opening site that is unencrypted & my info could be seen by 3rd party.  How do I re-encrypt Firefox or anything else (I'm not extremely IT savvy but am trying to learn now) so that I won't keep getting "unencrypted" message.

Also, I'm now constantly getting messages of unresponsive script.  Will fixing the unencrypted Firefox (&/or whatever else I'm supposed to encrypt) fix this, or is this a separate issue altogether? 

Started having these problems about 3 weeks ago.  I've run deep system scans w/BitDefender antivirus, have run free space checks & now have huge amount of free space on RAM.  I've got to get computer back to the way it was before:  i.e., encrypted; working @ faster speed; not getting kicked out of email & other apps I'm using all the time; not freezing up all the time; not getting these unresponsive script messages.  Thx much for any advice, suggestions!