Unable to choose or change order of clips in timeline FCP X

If the application is not behaving correctly, try deleting its preferences. To delete preferences, hold down command and option while starting the application and click Delete Preferences. The application will start in a default state, and open an "Untitled" library.

Reopen the library you were working on, set the preferences the way you like them, and try again.

In the timeline, you edit the clips in any way you want. There is no specific order - that would make it a useless video editor...

Drag then around to other positions, learn the keyboard shortcuts to insert at the playhead position (W) or append a clip to the end (E), and so much more.

In the browser, you can order by name, by date, by name, take, duration...

and more criteria if you switch your browser to list view: like in other Mac applications, you can click the header of any column to sort by it.

Maybe there is an issue on your mac, but at this point I have to say that it seems more likely to be some problem due to lack of familiarity with the application.

Can you post screenshots of what you're seeing and describe in greater detail what it is you're trying to accomplish? It's unclear what you mean by FCP arranges the timeline clips based on the number of the clip.

It's easy to change the sorting in the browser. Sort and group items in the browser in Final Cut Pro for Mac - Apple Support

Turn off background rendering in FCP Settings. It's almost never needed, especially for relatively modern machines. If there's a section that is effects heavy and can't playback in realtime, render just that section with Control-R.

If you select multiple items in the browser and drag them to the timeline, the sort order of the browser appears to dictate the order they are added to a timeline.

What are the exact specs of the media? Do you need to create proxy media? These takes time to create when importing.

Are you using Managed Media where FCP copies everything into the library when you import? This will also take time. Depending on your needs, you might research using External Media and set Import preferences to Leave files in place to determine if that would work better for your productions. https://www.apple.com/final-cut-pro/docs/Media_Management.pdf

you can't specify to have them arranged by content creation date

Media can be arranged on the timeline by content creation date.

--

Q1: What is your PC model? (Desktop →Apple mark →About this Mac)

Q2: What is the macOS version? (same as above)

Q3: What version of FCP is it? (Start FCP →Menu →FinalCutPro →About FinalCutPro)

Q4: Delete the FCP environment settings (start FCP while holding down option+⌘)

You can't reorder media in the browser either.

Browsers can be sorted by various criteria.

--

Q5: Are you viewing in filmstrip mode or list mode?

rendering takes an age when dragging more than one clip from even small sized clips from the browser.

Please turn off background rendering in the preferences.

Getting increasingly frustrated with FCP.. looking at Adobe Premiere as an alternative..

Choose your favorite editing app. There is an option not to use it. If you would like to resolve the issue, please provide detailed information to other users.

you can't specify to have them arranged by content creation date

Media can be arranged on the timeline by content creation date.

--

Q1: What is your PC model? (Desktop →Apple mark →About this Mac)

Q2: What is the macOS version? (same as above)

Q3: What version of FCP is it? (Start FCP →Menu →FinalCutPro →About FinalCutPro)

Q4: Delete the FCP environment settings (start FCP while holding down option+⌘)

You can't reorder media in the browser either.

Browsers can be sorted by various criteria.

--

Q5: Are you viewing in filmstrip mode or list mode?

rendering takes an age when dragging more than one clip from even small sized clips from the browser.

Please turn off background rendering in the preferences.

Getting increasingly frustrated with FCP.. looking at Adobe Premiere as an alternative..

Choose your favorite editing app. There is an option not to use it. If you would like to resolve the issue, please provide detailed information to other users.

Is this only occurring with pictures from the Photos app?

What version of FCP are you using as last year (with an earlier version) there were several problems when using Photos.

+1 for Ripple. For free FCP training, here are some suggestions:

Steve at Ripple Training’s 60 minute FCP tutorial overview https://www.youtube.com/watch?v=HqUP7Zgeuck

Final Cut Bro getting started  https://youtu.be/L3bZ-ETKZ8U

Izzy Video tutorials. Older so the UI looks different but the concepts are still correct. https://youtu.be/_jvyrnQpR1E?list=PLp5SAgbM8S87n1qvv34-PAU2zMHLlXyfb

I think a basic tutorial course from Ripple Training or macProVideo is in order, to save tons of time and headaches.

Along with what everyone else is saying here.