Have just re-installed on new computer, and have set up the default folder format that I want.
But I can't remember how to have this format also appear for search results? (eg. Date modified is not maintaining its position as the far left column).
Under Preferences / Folders / Folder Formats there is a Search Results format which should be all you need to edit (unless there are Path formats saved for specific named search results/folders, but there shouldn't be on a fresh install).
Close any open windows after changing the formats, to avoid cached formats complicating matters. Always open a fresh window to test with.
If it still gives the wrong results, hover the mouse pointer over the padlock icon on the status bar. Don't click it; just hover over it. What does it tell you about where the current format comes from?