43" TV UE43CU7100K can't adjust zoom and position on HDMI input - greyed out. Black bars around picture.

[ucanicant]

Just trying to set up my new TV on HDMI input from my PC's 4k HDMI output. The settings for zoom and position are greyed out so I can't adjust them. The problem is the picture has thin black bars on the left, right and top but not at the bottom. I'm pretty sure all I need is access to the zoom and position settings to correct that but can't seem to activate them.  Hopefully it's not a feature, this page (https://www.samsung.com/in/support/tv-audio-video/how-to-modify-the-picture-size-for-samsung-smart-t...) says I should be able to set picture size to custom and then I can adjust position and zoom but the only option in picture size is 16:9 standard, there is no other option!

I've updated to the latest firmware and tried all three HDMI inputs, made no difference. Nomal TV channels fill the screen fully, i.e. no black bars,  and the same PC 4k output also filled the screen fully with no black bars on my previous 4k Samsung TV which this new one will hopefully replace. Anyone know what I'm doing wrong?

[AndrewL]

@ucanicant: Just to be clear, do you have 16:9 selected, as this is what's leaving the black bars at the edges of the screen? If so, I would start by checking the output settings on your PC, and playing around with the available aspect ratios to see if this helps. Alternatively, head to Settings > All Settings > Picture > Picture Size Settings, and selecting 'Auto Wide' or 'Fit To Screen' to change the picture size automatically.

According to the user manual, the 'Custom' option SHOULD be available with an HDMI connection at all resolutions, although you may wish to try reducing the resolution output as a troubleshooting step to see if the option shows up in 'Picture Size'. 

[ucanicant]

"Just to be clear, do you have 16:9 selected, as this is what's leaving the black bars at the edges of the screen? If so, I would start by checking the output settings on your PC, and playing around with the available aspect ratios to see if this helps. Alternatively, head to Settings > All Settings > Picture > Picture Size Settings, and selecting 'Auto Wide' or 'Fit To Screen' to change the picture size automatically."

No, as I said, the only option in picture size is "16:9 standard", it's the only option available. There should be a "custom" option but there isn't. I tried different resolutions outputted from my PC, makes no difference. Also remember that the 4k PC output has been working fine on my previous 4k Samsung TV. I just unplugged the HDMI cable and plugged it into the new TV HDMI port, no other changes. It should work, but doesn't. I can see from the screen that I just need to increase the size and move it a bit but those options, move and size are greyed out because I can't select "custom", that's the issue