I am trying to create a bootable USB with windows 7 32 Bit.

I am using refuse portable and downloaded the iso image using it and wrote the image into a 16GByte flash drive.

I tried the generated flash drive in three different systems with a similar result: all reported that the USB is not bootable.

What am I missing here?

I created a Linux USB image and I am getting similar results from all three systems that I have.

Edit 1

I am using Rufus 3.19 and the screenshot of the setting is as follows:

There is no selection to indicate that the USB should be bootable.

Edit 2

On the old computer, when I am looking at boot sequence, I can see these options:

But I can not change the position of USB HDD and bring it to a higher place.
There is no hard disk attached to the system, so I assume it would reach this option eventually, but it doesn’t boot so I can not install it on a hard disk.