If you're looking to downscale footage (as opposed to upscaling it), you'll need to choose 'Bicubic Interpolation' under Filters > Scaler once you've entered the Process Tool.
After you've chosen Bicubic Interpolation, you'll have to choose the Custom option and enter the resolution you want to downscale to.
. . .
P.S. If you run into difficulties or need help, please reach out to us here or at firstname.lastname@example.org — we're always willing to lend an ear 👂