Image should keep proportions and be responsive

Hi all!

I am just getting started with an App and I uploaded a visual from the library and the proportions change, based on the set frame.

But instead I would love if the proportions stay and it’s just cut if it’s to big.

YouTube says I should use “run mode rendering” - but this option doesnt exist in my interface. Below some pictures. Thanks in advance for any support!

you can use fixed width in lay out tab

In Dynamic Image put the URL in an Arbitrary Text operator.

You’ll then have access to some scaling options.