Hello checko below file into your template layout xml
wishlist.xml
<action method="addLinkBlock"><blockName>wishlist_link</blockName><prepare/><urlParams/><position>10</position></action>
checkout.xml
<action method="addCartLink"><prepare/><urlParams/><position>30</position></action>
customer.xml
<action method="addLink" translate="label title" module="customer"><label>My Account</label><url helper="customer/getAccountUrl"/><title>My Account</title><prepare/><urlParams/><position>100</position><liParams/></action>
<action method="addLink" translate="label title" module="customer"><label>Log Out</label><url helper="customer/getLogoutUrl"/><title>Log Out</title><prepare/><urlParams/><position>50</position></action>
<action method="addLink" translate="label title" module="customer"><label>Log In</label><url helper="customer/getLoginUrl"/><title>Log In</title><prepare/><urlParams/><position>50</position><liParams/></action>
we will see Default Position In Magento
My Account = 10 Path-> app\design\frontend\default\default\layout\customer.xml
Whislist = 30 Path-> app\code\core\Mage\Wishlist\Block\Links.php
Mycart = 50 Path-> app\code\core\Mage\Checkout\Block\Links.php
Checkout = 60-> Path-> app\code\core\Mage\Checkout\Block\Links.php
Login/Logout = 100 Path-> app\design\frontend\default\default\layout\customer.xml
1000000
but the links are added in the xml order like the position is relative only to the links being added at the same time.