To select a specific LLM (Large Language Model) to interact with, click on the Model button, located on the top left of the central part of the interface right next to the menu button. After clicking the button a drop down menu will open. You can now chose between all available models:
Depending on the plan you have subscribed for, you will have access to various models , including OpenAI's GPT models and the Gemini, Anthropic and Mistral models and also to Deepseek.
Keep in mind, that you can onyl change the model when interacting with AI without using the AI subunits (Agents) as they have their models assigned by default for optimal performance.