Final Cut Pro preview window got really tiny

You can manually resize panes... Mouse over the edges until you see a cursor like:

then click and drag out the size.

There are accessible cursors at each side and the bottom to resize the storyline's height.

I cant get it back to normal.

If the screen layout becomes strange, press ⌘0 to return to the default.

--

⚫︎Return to default *subtitles ON

https://youtu.be/07ZSne2m5iQ?t=100

⚫︎Save layout presets

https://youtu.be/07ZSne2m5iQ?t=246

LocaAlicia's method should work and is simple.

Another easy way to return FCP to its default (as new) settings and appearance is to delete the preferences.

Hold down the command and option keys as you launch FCP until a window pops up whereupon you click the Delete button.

This technique can also be used for troubleshooting whenever FCP behaves strangely.

You already got some good advice, but it seems to me that you may have simply to set your FCP window to fit the screen, before applying the other suggestions, maybe.

Hold down the Option key and click the green button at the top left.

Why don’t you show the Viewer? Make the Viewer the active pane and press Shift-Z to fit to window.

You could also try enabling the Inspector pane to see if that resizes the window.

Try closing the event viewer in the Window menu for more space.

Please show the full window so we can see the control settings. The rectangle in the corner indicates you’re very zoomed out.