im writing a book and want to change layout to fit a kindle but don't know where to start any suggestions? I know how to change file type?

Read all of these at Amazon KDP

https://kdp.amazon.com/help?topicId=A37Z49E2DDQPP3

https://kdp.amazon.com/help?topicId=A36BYK5S7AJ2NQ

https://kdp.amazon.com/help?ref_=TN_help

And basically, unless you are writing a picture book, you do NONE of what you were asking. Your goal is to NOT force fonts/typefaces at all, NOT force any kind of page size or layout. Your goal is to have practically plain text with just possibly a larger size for chapter titles. The USER gets to choose their font and font size when reading. The text should adjust to the size of the USER's reading device or app. YOU provide almost plain text that forces no fonts or layout.

BTW - a good free ebook text editor is yWriter - designed for writing books. A non-free more advanced but similar program is Scrivener.

If you ARE writing a picture book then buy and read this:

Pictures on Kindle: Self Publishing Your Kindle Book with Photos, Illustrations, or Other Graphics, or Tips on Formatting Your Images to Look Their Very Best (New Self Publishing)

http://www.amazon.com/Pictures-Kindle-Publishing-I...

And read about KDP's new Kid's Book Creator

https://chrismcmullen.wordpress.com/2014/09/04/how...

Amazon also offers a Comic Creator

Just google this there are scores of articles of formating for kindle

I have tried but am unable to get any of them to actually work correctly