Vim 8.1: cursor position not saved.

Hi: I am within vim editing a file and the cursor is in a given position. Now I exit (:wq command). The next time I edit that file, that is when I invoke vim with the same file name, the cursor appears in line 1 column 1. This happens every time I run vim on a file already edited with vim. How can this be? I thought vim always saved the cursor position and, in fact, this was the case when I ran vim under Slackware.