I have been taught to use two spaces after the period in high school. I do not like the auto formate of one space. I have read about reasons for single space. I enjoy the spacing of the typewriter.
On the other hand, you might want to read this answer, and the Q&A it belongs to on punctuation after full-stops. Word processors are not typewriters!
To be able to add as many spaces after the punctation uncheck Ignore double spaces, under option, on the AutoCorrect Options Pane.
The convention was only ever after full-stops (“periods”) in any case, not after commas, etc.