# How to change the arrows tips for the whole document?

After I asked this question: What is "\SelectTips{a}{b}" (and how to increase the head of an arrow's head?)
I'd like to know one more thing: I want to change it (the arrow tips) for the whole document, i.e. - right now, if I want to change the arrow tip I need to put the command \SelectTips{eu}{} (for example) at math-mode for every formula or graph that I make (especially at xy-pic).

Is there a way to put it at the Preamble that it will influence all the document? (all of the arrows tips at math-mode).

Thank you!

You can put \everyxy={\SelectTips{eu}{}} in your preamble:
\documentclass{article}
$\xymatrix{ A_1\ar[r]\ar[d] & A_2\ar[d]\\ A_3\ar[r] & A_4 }$
$\xymatrix{ B_1\ar[r]\ar[d] & B_2\ar[d]\\ B_3\ar[r] & B_4 }$