The default page title in Joomla 1.5 is “Welcome to the Frontpage”.
Step 1: Login to Joomla admin area
Step 2: Go to Menus and then Main Menu
Step 3: Select Home
Step 4: Choose Parameters and then System
Step 5: Go to Page Title.
Step 6: Type in the new page title you wish to use and save the change.
Next time you open your website, the new page title will show up in your browser.