MediaCoder

At the bottom left, click the "Picture" tab. Then check "Resize" and select the new video resolution from the "Resize" drop-down menu. Pay attention to export to another folder, for safety never export to the original folder. Now at the top of the panel you can press the "Start" button to export the...

I got no problem to set the output resolution to my convenience.

The video item being selected at the top:

• Down left of the main panel, open the tab "Picture".
• Check the box beside the button "Resize"
• Then adjust to your preference in the combo-box.

That's all.