A guess or two:
1. You have 16:9 track selection* for 4:3 video/images
2. You have not adjusted the image/video, right click clip in track and select "Set Clip Attributes".

* See top of Edit Workspace for 4:3/16:9 drop down selection.

If you have a 4:3 setting in the Edit Workspace/Track/Preview, the Produce file will offer only 4:3 frame size.

Dafydd

Yes, thanks Dafydd
I could not see any 4:3 settings set and only 16:9.
Have attached pic of timeline and you can see preview window is chopped a bit (although no black border now) and if you look at clips in timeline they are not clipped?
2nd pic shows video manager YouTube with chopped top and also has not generated any thumbnails and after some hours thumbnail is still not showing in YouTube page. This clip took quite a long time to load and thought it may not load.
Seems like may be other issues and will redo to see if can fix.
Another video have started looks fine so just wondering what happened.

Peter PD Ultra 16.0.2524.0 ~ Windows 10 Pro Intel(R)Core(TM)i7-4770 CPU @3.40GHz ~ AMD HD-7800 Series APU with Radeon(tm) HD Graphics ~ 16GB RAM ~ WD 1Gb Primary HD ~ Hitachi 500Gb ~ Buffalo 8Gb DriveStation ~ WD 1Gb ~ Medion 500Gb ~ Canon Legria HFS10 ~ W/ FH

Cant see anything untoward in either image supplied(re PDR12 issue).
Dafydd

I will step in and add some information as to the thumbnail issue.

When I go to your YouTube channel I do see a thumbnail for the particular video you show in the image you uploaded here.

In your uploaded image ( PD12 ScrnSht 2.jpg), it shows the "Customized thumbnail" option and it appears to be highlighted, as if you you are wanting to upload a custom image. This is where you need to make a customized image that you wish to be displayed.
Sometimes it will show three options, but then when it doesn't try using this option.

Here's how to change a thumbnail at any time:

To upload a custom thumbnail for an existing video:

Go to your channel Video Manager.
Locate a video and click the Edit button.
Click the Custom thumbnail button and upload a thumbnail.
Once the thumbnail is uploaded, don't forget to click the "Save Changes" button.

Custom thumbnail Size

Your custom thumbnail image should be as large as possible, as the image will also be used as the preview image in the embedded player. We recommend your custom thumbnails:

Have a resolution of 1280x720 (with minimum width of 640 pixels).
Be uploaded in image formats such as .JPG, .GIF, .BMP, or .PNG.
Remain under the 2MB limit.
Try to use a 16:9 aspect ratio as it's the most used in YouTube players and previews.

This is what I do and not had any issues. Hope this helps. Thanks,
Bill in Texas

PD-12, PD-14 and PD15 is installed on this iMAC computer under BootCamp, and PD's are running great:
DxDiag Info:
System Information
------------------
Operating System: Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 Language: English (Regional Setting: English)
System Manufacturer: Apple Inc.
System Model: iMac11,2
BIOS: Default System BIOS
Processor: Intel(R) Core(TM) i3 CPU 550 @ 3.20GHz (4 CPUs), ~3.2GHz
Memory: 4096MB RAM
Available OS Memory: 4022MB RAM
Page File: 2031MB used, 6010MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: 144 DPI (150 percent)
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 32bit Unicode

PD-12 PowerDirector Ultra: 12.0.3403.0

PD-14 PowerDirector Ultra: 14.0.1728.0
SR numbers: VDE14

PD-15 Power Director Ultra
15.0.1725.0

Thanks Bill, interesting your using PD12 on iMac and runs well. Thought all iMacs used Final Cut Pro.
But my real issue was that somehow that particular video was cropped completely and I could not work out why. Will do again from scratch and should be OK.
Have started another and all seems fine.
The original upload did not produce any thumbnails so had imported one in to it.
Ah! this is how it all happens... Windows 7 Ultimate 64 inside BOOTCAMP on a iMAC
Thanks again and hope the Northern Polar Vortex has not frozen you out in Texas. PD Ultra 16.0.2524.0 ~ Windows 10 Pro Intel(R)Core(TM)i7-4770 CPU @3.40GHz ~ AMD HD-7800 Series APU with Radeon(tm) HD Graphics ~ 16GB RAM ~ WD 1Gb Primary HD ~ Hitachi 500Gb ~ Buffalo 8Gb DriveStation ~ WD 1Gb ~ Medion 500Gb ~ Canon Legria HFS10 ~ W/ FH