Same dimensions but only half the ad is visible

For the Google Adsense ad I chose Images of 120 x 240. In the plugin I chose Vertical banner 120 x 240. But then only the left half of the ad is visible. To solve this I changed this in the plugin to 200 x 200. But obviously that is not a permanent solution. I get the impression that Google uses height x width and the plugin width x height. If that is true than why doesn’t the plugin have a horizontal 240 x 120?

https://www.ads-software.com/plugins/adsense-plugin/