Update app.py

app.py

@@ -629,10 +629,10 @@ elif st.session_state.current_index < len(st.session_state.data):
 elif st.session_state.current_index == len(st.session_state.data):
     st.write(f"**Thank you for taking part in this study!** \n ")
     if st.button("Previous"):
-        navigate(-2)
+        navigate(-1)
 
 # Navigation buttons
-if -2 < st.session_state.current_index < len(st.session_state.data):
+if 0 < st.session_state.current_index < len(st.session_state.data):
     if st.button("Previous"):
         navigate(-1)