Hi,

On Genio, select the Form you have the field representing the image in. 

Open the Form Editor for that form and then select the field that has the image (direct click on the image or through the field explorer on the right). Select tab "Properties" and adjust "Size" properties :

Adjust those according to your requirements.

Remark: Please note if the platform and language selected (top options) are the right ones and correspondent for the client solution you want to make it work. If live version is not responding to this changes, please check if the controls are well suited for the generation you're doing (platform and language should match the client).