@falbriard glad you have it working.
In UIFlow2 there is now the Project zone. I'm writing a book on UIFlow2 for the CoreS3 (but the instructions works on any S3 series device) you can find a work in progress copy on face book but I'm slowly porting the books examples to Project Zone.

@mono-mono go into uiflow2 and change the name by clicking on the device on the bottom of the screen

Then probably the fact that Atom S3 currently supports only tiny subset of UIFlow features should be made clearer in the product description. I bought an Atom Matrix for a DIY watering project, was fairly impressed with the device (and the whole M5Stack concept) and decided that small local display for current humidity etc would be even better. So I bought the new AtomS3 (described as supporting UIFlow development platform) and currently can't connect it neither to my Watering sensors nor the MQTT data collection server. I will switch my development back to the Matrix and will be looking forward to switch it again when the features I need will be supported in UIFlow 2