Hi Fabien
As far as I can remember there is no global option to change timeouts for webservice calls. calls in this dated ivy version. But, you can define a timeout on each webservice call activity: https://developer.axonivy.com/doc/5.1.13/DesignerGuideHtml/ivy.processmodeling.html#ivy-processmodels-elements-webservice
If you have to change many elements to apply the same timeout setting. Consider using a scripted value from a data class attribute which you define once and read on every web service client call activity into the timeout field.