Hi,
welcome to the board!
It depends on the document class. For example, the KOMA-Script classes do this by default. So you could solve it by switching from report to scrreprt or from book to scrbook. The KOMA-Script classes have further advantages.
Or, if you would like to use standard classes, you could use the
titlesec package for customizing the chapter headings. With titlesec, use a
hang
style, which is like section headings, instead of a
display
style, which is the original style in standard classes.
Stefan