solved issue update button click twise to update

app.py

@@ -91,15 +91,12 @@ def main():
             on_change=update_parameters_change,
         )
 
+        
         if st.session_state.is_parameters_changed:
-            if st.button("Update"):
-                st.session_state.model = chat_model
-                st.session_state.dataset = "DEFAULT"
-                st.session_state.show_source_files = show_source
-                st.success("done")
-                st.session_state.is_parameters_changed = False
-                return
-            
+            st.button("Update", on_click=parameters_change_button, args=[chat_model, show_source])
+                
+             
+
         st.markdown("\n")
 
         # if st.button("Create FAISS db"):
@@ -126,13 +123,19 @@ def main():
 def update_parameters_change():
     st.session_state.is_parameters_changed = True
 
-def get_answer_from_backend(query, model, dataset):
+def parameters_change_button(chat_model, show_source):
+    st.session_state.model = chat_model
+    st.session_state.dataset = "DEFAULT"
+    st.session_state.show_source_files = show_source
+    st.success("chat parameters updated")
+    st.session_state.is_parameters_changed = False
 
+
+def get_answer_from_backend(query, model, dataset):
     response = qaPipeline.run(query=query, model=model, dataset=dataset)
     return response
 
 def show_query_response(query, response, show_source_files):
-    
     answer, docs = response['result'], response['source_documents']
  
     st.write(user_template.replace(