Slider images too small

I have been searching all day on google for support with my slider. I am using Activello theme and when I enable the slider, the images are quite small with grey sides. I’d like them to be large like the demo.
After searching, I downloaded the Regenerate Thumbnails plugin which i thought might fix the size of the images. However nothing has changed. When I go into each individual photo I cannot edit the size (a red exclamation point comes up next to it).
Most of my images have been created on Canva - using the ‘blog title’ design. Could this be where the sizing has gone wrong?
How can I fix this?
Thankyou so much for your help in advance!! :slight_smile:

Hi @grace,

I hope you are well today and thank you for your question.

Could you please share me your site URL where it’s happening so that i can troubleshoot it?

Kind Regards,