Macos – (Mac OS X) How to adjust the default popup size of Quick Look in Finder

The only "real" answer to this issue that I have seen is to click on the Finder in the dock. When the window opens, immediately resize that window and close it. Don't move files, etc, simply close the window. Now each opened window will reflect the same size as the original. By all means, this is a 'hack' and it isn't something permanent. If you open your Finder windows via command + n do the same as above to set the size.

One (very unrecommended) option would be to assign a shortcut to an AppleScript like this. There's an open bug in 10.7 that makes the script more or less unusable.

tell application "Finder"
    if insertion location as alias is desktop as alias or current view of Finder window 1 is in {icon view, column view} or selection is {} then
        tell application "System Events" to tell process "Finder"
            click menu item "New Folder" of menu 1 of menu bar item "File" of menu bar 1
        end tell
        return
    end if
    tell application "System Events" to key code 124 -- right arrow
    set p to item 1 of (get selection)
    try
        set f to make new folder at p
    on error
        set f to make new folder at container of p
    end try
    set selection to f
end tell
tell application "System Events" to keystroke return