Hey!
You can choose Block Options in the survey and add the text or symbol you want for the previous or next button. This has to be done for each block you have. If you have access to Look and Feel editor, you can make the changes there under General. Back arrows will not show unless you enable in Survey Options and they will not show after branching in the survey flow.
Here is the support link for step-by-step instructions.
Thanks!
Sabrina

Thank you, Sabrina!!
I understand about changing the text or symbol for next button.
But I still don't know about hiding (or doesn't show) next button.
Can we do that?

Hi Ruuho,
Please refer to this post:
https://www.qualtrics.com/community/discussion/249/how-can-i-hide-the-previous-and-next-buttons-on-my-survey

Thank you Mr. Mohammedali !!
I could hide the next button!!