On a fresh page of questions I see the statistics of each question (number of views, votes, answers) placed in a horizontal way, but upon visiting a questions and coming back it becomes vertical (taking more room, it appears). Is there a way to fix the format to horizontal?
It seems that you are talking about the main site, which is shown when you click on that big banner on the top of the site (or, if you want to get there from meta, if you click on the link named main in the right upper corner); and about the questions tab, which is shown when you click on the word questions (just under the big mathematics banner).
They display differently simply because they are two different web pages.
I think that the difference is rather natural. By putting statistics more to the left, there is more place for the question; which is needed because on the question tab the beginning of the question is shown and it needs some space. (Whilst the main page displays only titles and basic stats.)
The main difference between the two views that we are talking about is in the vertical space allotted to each question. The front page shows them in a more condensed way, which makes it possible to put
90 questions on the front page of StackOverflow (only
48 on Mathematics, though). Here the counts must be put horizontally to minimize vertical dimension.
On the Questions and Unanswered tabs (and, to a lesser degree, in search results) questions are given more vertical room so that the users can get a brief preview of each. Given the larger vertical dimension, it makes sense to stack the counters differently, freeing up some horizontal dimension (which is
728 px in all views). Your remark
(taking more room, it appears)
is incorrect: the increase in vertical dimension comes from including the preview, not from the counter. Even when the preview is mere two lines, the counters fit with room to spare: