Under Lightroom 6 on Mac OS X 10.11 El Capitan (GM seed), the keyboard shortcut for the Find command and the Full Screen command swap places after 30 seconds.
Lightroom has always used Command-F to be the Find command. When I first launch Lightroom and I click on the Library menu, I see "Find (Command-F)" and under the Window menu, I only see "Full Screen Mode". Pressing the command key shortcut engages the Find command as I was used to.
After about 30 seconds, the keyboard shortcut mysteriously and silently switches places. Now, when I look under the Library menu, I only see "Find" and under the Window menu, I see "Full Screen Mode (Command-F)" and pressing the key combination changes the Full Screen mode.
I would love to see Lightroom return to the previous behavior of consistently engaging the Find function with Command-F because that is what I am used to.