How to change video orientation from Portrait to Landscape?

if it is on the computer already, just open it, and then maximize the window using the square icon in the top right corner.

you cannot "fill the screen" unless you rotate or crop the video in an editor, as computer monitors are landscape.

photo manipulation software on the PC

Open the file

Choose Edit > Select All

Then go to Video > Filters

Select Add

From the list, choose Rotate

Choose the option you want (Rotate left, right, 180) and select it

The video should then display in two versions, one landscape, one portrait. The image might be distorted in the portrait version. It seems to work ok once you actually play the clip again

You can preview the portrait version’s playback to check it’s OK by going to File > Preview Filtered

Once you’re happy, save out the filtered portrait version as an AVI from File > Save as AVI