MacOS – Always Automatically ‘Right-Size’ All Finder Window Columns Individually

In column view in the Finder, you can resize columns by positioning the mouse pointer over over the thin line that separates column panes, and dragging it to the left to make it narrower or to the right to make it wider.

To make the Finder remember the new width, hold down the option key(⌥) while dragging the pane separator to the desired width.

The best documentation I can find on this from Apple alludes to the fact that holding down option resizes "all columns at once" but does not explicitly say that this makes the change persistent.

What works for me (although some quirks remain) is this: in view options (CMD-J) set up your finder window exactly how you would like them all to be. Make sure to check "Always open in ... view" and "Browse in ... view". When you're happy, click "use as defaults". Then open a terminal window and enter the following command:

sudo find / -name .DS_Store -delete; killall Finder

(it prompts for password and generates some "no permission" errors. Could take a minute or two)

It removes all the .DS_Store files from your folders. These are hidden files that contain the view settings of a specific folder (you might have noticed them when opening a mac USB stick on a windows machine or whatever).

It's not perfect, right size is relative to your finder window size i believe, but it's much better than the frustrating craziness that comes from every folder having different settings...

CMD-J opens the view options. When in that window, Fn will change the "Use as Defaults" button to "Restore to defaults". That's pretty close to a shortcut, I'll do some digging to find out how to make it full circle...