Safari won't quit using High Sierra 10.13.6 on MacBook Pro Retina, Mid 2012

1. Try Force Quit  Safari from Activity monitor.

    1. Click the Spotlight icon in the menubar.

    2. Start entering Activity monitor in the search bar next to magnifying glass icon.

    3. Click Activity Monitor

    When Activity monitor opens: 

   4. Enter safari in the search box at the top right corner.  Select CPU if not already. 

   5. Select Safari under Process Name.

   6. Click "Force Quit Safari", the "X" button.

   Activity Monitor. https://support.apple.com/en-us/HT201464

2. Close all windows and quit all applications.

    Hold "option" key down and click "Go" menu in the Finder menu bar.

    Library will appear between “Home” and “Computer” entries in the dropdown.

    Select "Library" from the dropdown.

    Click  the “List” view button  in the Finder toolbar.

  Move these files to trash and test.

 1. Click open the Caches folder and scroll down the list.  

     Click open the   com.apple.Safari folder.

     You should see the Caches.db file.

     Right click on it and choose “Move to Trash”.

 2. Scroll down the list, click open the  Safari folder, select History files and LastSession.plist

     Right click on it and choose “Move to Trash”.

3. Scroll down the list and click open the Saved Application State folder.

    You should see the com.apple Safari.savedState folder.

    Right click on it and choose “Move to Trash”.

 4. Close Finder window.

     Restart and relaunch Safari holding the shift key down.

     Test.

Download this program which was written by Thomas Reed, a long time poster. The program will search for malware/adware The program will do the work for you which makes it easy. 

Malwarebytes Anti-Malware for Mac      10.10 and later

Malwarebytes uninstall

      Download EtreCheck: https://etrecheck.com/maspro  and post the report here.

      Click, “Free Download” button and then  “Click to download” button,

      open Downloads folder, click on it to open, and then select ”Open”.

      Click on the bouncing  EtreCheck icon in the Dock.

      “Choose a problem” from the popup menu box, and then “Start EtreCheck” in the dialog.

      Click “Share Report” button in the toolbar, select “Copy to Clipboard” .

      Please  post the report here when you reply.

    Download Safari Technology Preview and try as a test.

    Safari Technology Preview is a self standing developer version of Safari with some advanced features.

    Bookmarks will be automatically imported.

    After testing, you can remove it from Applications folder if you wish. 

    https://developer.apple.com/safari/technology-preview/

I was experiencing this same problem with my Mac today as well. Followed all of the recommendations to remove PLISTS, caches, etc. Downloaded the Malware free trial below too. Nothing seemed to work. I even did the PLIST, SMC, and PRAM resets on start up.

Then I tried disabling/uninstalling the Safari extensions. I had read that in one of the threads around here in the community, but can't remember who recommended it. (Sorry, wish I could give credit where credit is due.) I only had 4 installed. Once I disabled those, the problem stopped. Then I turned them on one by one and restarted Safari to test it out. I ended up deleting the Grammarly extension because it wouldn't start up again or work. Figuring it was that extension that was causing ruckus for me. Try disabling extensions first.

Safari works just fine now.

I have the same question: when I used the option+command+esc to force it to quit, it still kept showing.

My safari also has another issue but I don't know how to solve:

I use GOOGLE as my search engine. Whenever I googled the information, I was redirected to BING.

How can I solve those two questions?

See if anything here helps.

safari app won't quit - Apple Community

You are welcome. Glad to help.

I have solved both issues by the suggestion of previous reply from Eric Root. Thank you.

Good.