Responsive grid layout from dreamweaver tutorials [how to insert a responsive image carousel and testimonials slider?]

I have recently created a website by following the dreamweaver responsive grid layout tutorial.

When I insert the image carousel from the bootstrap components, the webpage moves from central to left aligned. Although still responsive to different devices, I was wondering if you knew how to make the website centralised again?

I don't know whether the best method is to alter the bootstrap component carousel or whether there is alternative code that I can embed that will give the same outcome.

Along the same lines, I would also like to insert a testimonial slider at the bottom of my webpage. I didn't know what the best method was to adopt so that the page remains responsive and centralised within the grid layout.

I would appreciate any suggestions.