Use turbo mode (shift click on green flag) to generate the set faster. The more iterations, the slower it will take to generate. Using this project on Turbowarp would be beneficial.
Using this project on Scratch will be very slow. Put this project on Turbowarp to make it faster. Click anywhere on the mandelbrot set to change the horizontal and vertical shift. Once satisfied with the location (where the white dot is), you can change the zoom. (change zoom only AFTER changing the shifts.) After that, click the green flag again to regenerate the mandelbrot to your selected location and zoom.