The PhET animation runs in your browser.  Depending on your computer and your browser, the program may not be able to maintain the animation speed when you have 3 light bulbs in parallel.  It then shows the battery overheating.
In a real experiment, if your battery was overheating, you could just connect a second battery in parallel.  But that does not work in the simulation, because it reduces the animation speed even further.

So what can you do?

You can choose a lower voltage for the battery, maybe 25 V or so.  Just state that you have picked a different voltage and do all of activity 1 with that different voltage.  That is what you would do if you did the experiment with a variable voltage supply and the supply was overheating.  The simulation can then maintain the animation speed.
 

(You could also choose bulbs with a larger resistance. If you do that all bulbs should have the same larger resistance and you have to state which resistance you used.)