I have a Seeed D1001 display running Tessera - lost the ESPHome YAML

Can anyone advise? I have several small Screens running Tessera in my Home Assistant setup, which has ESPHome built in. In each case, there is an ESPHome YAML file with the basic Wi-Fi setup in it. For some reason, the last device I fitted om Teserra is a Seeed D1001 and although it works, I simply cannot find the YAML file in ESPHome. I'm having trouble taking the device from room to room, and because I have a network of several SSIDs, I want to make sure I've got that correct in the YAML file. But it is nowhere to be found.

Any ideas as to how to recreate the YAML file in ESPHome so that I can check the multiple Wi-Fi setup without starting from scratch because I already have two full screens in the D1001 and I'd rather not lose them.