This has not been tested on devices with custom manufacturer UI's, such as HTC Sense. I can't actually check (as I don't have Sense anymore), but I would guess that it won't work as the lockscreen is completely different when using a manufacturer UI.

This morning on Reddit, I spotted an awesome post titled "I got rid of that stupid lockscreen clock font...," showing nothing more than a screenshot. When asked for details, the Reddit community responded in typical supportive fashion, explaining which file needs to be replaced. It turns out it's quite a simple thing to do for rooted users, requiring only that you copy a font from your PC to your SD card, then replace one file. With the help of two apps, the process is even faster and easily reversible.

Estimated time: 10 minutes

Difficulty: Low

What's Needed

Type Fresh

[qr]net.pixelpod.typefresh[/qr]

Type Fresh is a simple, free app that makes it easy to change the fonts on your device. True alpha-dog techies will probably scoff at using an app for something as basic as overwriting a file on your phone with a new one, but it's small, easy to use, and offers friendly features like the ability to backup the font before you overwrite it.

AndExplorer

[qr]lysesoft.andexplorer[/qr]

AndExplorer is required for Type Fresh to work properly. It's a free file explorer - not much more to say other than that. It's similar in nature to File Manager or Astro.

Font

Obviously, you'll need to know what font you want to use. I used Myriad Pro because it's what I used for the Custom Android Phone 7 theme I made just last weekend. The beauty of customization is that you can use whatever you want.

Getting Started

Believe it or not, if you've downloaded those two apps, you're already halfway finished.

Putting The Font On Your Phone

  1. Connect your device to your PC, and enable USB transfer. The autoplay box should appear.
    autoplay
  2. Click on "Open folder to view files" or manually do it yourself by going to My Computer.
    window
  3. If you have Windows Vista or Windows 7, you can hit Start and type in the name of the font. Again, I used MyriadPro. Once you find the file (.ttf or .otf), right click and select Copy.
    myriad
  4. Return to the folder for your phone. Right click in an open area and select Paste.
    pasted
     

Configure Your Phone

Note: You may want to backup the fonts first. To do so, open Type Fresh and hit Menu -> Backup Fonts. It will automatically back them all up.

  1. Fire up Type Fresh.
    TypeFresh1
  2. Tap on Clockopia.ttf (should be at the top). A new menu will appear, showing the default directory of /sdcard/Fonts.
    typefresh2
  3. Our font is in /sdcard, so we'll need to tap [Go to up folder].
    typefresh3
  4. Select clockopia.ttf (at the bottom).
    typefresh4
  5. Hit your Menu button, and tap Apply Fonts.
    typefresh5
  6. Reboot your device.

That's it - you're finished! Enjoy the fruits of your labor!

Thanks to Redditors Ron_ for the post and lyam23 for details.

Source: Reddit