Live Mode Editor is Terrible

1. Switch to Design view (Ctrl/Cmd + Shift + F11).  It makes a big difference when editing code, especially PHP scripts.

2. Are you working with valid code denoted by a green check mark?  If you see a red X, click on it. Fix all reported errors and save your document.

See screenshot.

3. If you continue to experience erratic behavior, try Restore Preferences.

https://helpx.adobe.com/dreamweaver/kb/restore-preferences-dreamweaver.html

Hope that helps.

In the past several versions of Dreamweaver (currently 21.3), the Live Mode editor is absolutely horrible. 

Example problems:

1. Click to position the cursor, scrolls the page and the wrong location in the document is selected.

2. Type text after getting cursor positioned.  Random characters are deleted.

3. Non-breaking space characters are randomly inserted.

 

Why do I keep trying, year after year?  All editing must be done in the Code View.

By @affectionate_Spirit16B8

Don't expect any improvements soon, DW is what it is now, unfortunately a fading light. I would suggest that you look at something like Pinegrow editor, which is still being actively developed, if you require 'visual design assistance' or maybe 'Wappler' if you can afford the high entry subscription and have the requirments to do more complex work.