doc: documented the change of models

Author: geoffroy-noel-ddh

docs/changing-models.md

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+# How to change the large language model (LLM)
+
+## On the Questionnaire and Highlighter
+
+All the responses displayed on 
+[the questionnaire and highlighter prototypes](https://kingsdigitallab.github.io/algorithmic-justice/nlpui.html) 
+come from the same model selected in the Settings tab.
+
+![Setting tab, model drop down](settings-model.png)
+
+By default the drop down is set to a particular model 
+(`gemma3:4b` in this example).
+
+You can select alternative models in the drop down 
+then return to the Questionnaire 
+and click the "Ask" button next to each question to see the response.
+
+To save you from clicking all the Ask button 
+you can also pre-render all the responses at once 
+after changing a model
+by pressing the "Show all responses" button 
+at the bottom of the Settings screen 
+then return to the Questionnare tab.
+
+![Settings tab, show all responses button](settings-show-all-responses.png)
+
+Whenever you change a model 
+its name is updated in the URL of the web page 
+which is usually visible in the address bar of your browser.
+You can therefore bookmark, copy and share that address 
+and the next time it is opened, that model will be pre-selected.
+
+## On the integrated prototype
+
+Similarly all responses displayed on 
+[the integrated prototype](https://kingsdigitallab.github.io/algorithmic-justice/poc3.html) 
+come from one model. 
+
+The model name is mentioned under the algorthm section. 
+To get there, click "Explain algorithm" button under the question table.
+
+![model in poc3 web page](poc3-model.png)
+
+There is no settings tab on this prototype 
+because it is designed for end-users or tests.
+An alternative model can be specified via the URL.
+
+For instance, this URL [https://kingsdigitallab.github.io/algorithmic-justice/poc3.html?model=qwen3.6:27b](https://kingsdigitallab.github.io/algorithmic-justice/poc3.html?model=qwen3.6:27b) 
+will select qwen3.6:27b and show its responses in the question table.
+
+This allows you to share a link with other users or tester 
+who will only see that particular model 
+when the integrated prototype loads in their browser.
+