Remote control and screen sharing

Hi I have been using the free Zoom to teach online. I have always shared my screen easily and given the children remote control. But recently when I try show a video it doesn't show the video - gets stuck on the first 'screen.' When giving remote control the children can move the cursor but not click and choose an item. This all worked very well until now.

We have all updated our Zoom. Please help - any suggestions welcome.