This is called pagination- it’s controlling how many questions appear on a given page in a quiz, after doing this you can manually add or remove these automatic page breaks. Adding new questions to a quiz after applying this setting will enforce that pagination on all new questions.
Enter the Quiz you wish to modify
Locate the Actions Menu (gear icon) from the top-right corner of the page
Select the Edit Quiz option
At the top of the Editing Quiz page, click the Repaginate button
A menu will appear
Set the value in the provided box (how many questions you want per page)
Click the Go button
NOTE: We advise that you not put too many or too few questions on any page in Moodle as quiz data on a page is not saved until a student moves onto the next page. It is a best practice to write quizzes that keep a student on a quiz page for no more than 5 minutes, as this will minimize a loss of data (in case of connection loss) and will keep the student from needing to constantly reload Moodle (which can increase the chance of connection loss).
A page break can NOT be added before the first question or after the last question of a quiz.
Enter the Quiz you wish to modify
Locate the Actions Menu (gear icon) from the top-right corner of the page
Select the Edit Quiz option
Repeat as desired
Locate the last question you want to appear on a given page
Click the add page break icon 
to the left and slightly below the question. A new page break will appear
Enter the Quiz you wish to modify
Locate the Actions Menu (gear icon) from the top-right corner of the page
Select the Edit Quiz option
Locate the page break you wish to remove (e.g., Page 2)
Click on the remove page break icon 
to the above and left of the page break
Repeat as desired