Cannot change homepage of Safari - locked to apple.com

You can also try selecting Homepage in Safe Mode.

Startup in Safe Mode.

Launch Safari.

Set Homepage.

Quit Safari. Click Restart at the bottom.

 Start up in Safe Mode. https://support.apple.com/en-us/HT201262

If Safari's home page is stuck

In some cases, after being changed by adware or malware, Safari's home page can become stuck. You will be able to edit the Homepage field in Safari's preferences, but the change will not stick. This appears to be a bug, and there is an odd workaround. Try this:

1. In Safari, choose Preferences from the Safari menu.
2. In the window that opens, click the General icon (if necessary)
3. Enter your desired home page in the "Homepage" field, but DO NOT press return!
4. At the top of the window, click any of the other icons (eg, Tabs, AutoFill, etc).
5. You may see a prompt asking for confirmation for changing the home page. If so, confirm.
6. Switch back to the General page and check to make sure the home page has been changed.

Ref: https://forums.malwarebytes.com/topic/236261-how-to-remove-weknow-malware-and-others/

Safari > Preferences > General

New windows open with:

Select "Favorites" instead of Homepage.

Does it work?

If you have Extensions installed, disable them and test.

Safari > Preferences > Extensions.

System Preferences > General

Is there any Profile listed?

 If this doesn't help,  download EtreCheck, https://etrecheck.com/maspro  and post the report here.

      Click  “Click to download” button,

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

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

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

      Paste the report when you reply.

      Note

      This is a diagnostic test.

      If 5000 words limit applies:  Split the report into two parts and post as two separate posts.