The reason I have chosen Illustrator to demonstrate this is because, I think it remains the best program for small amounts of text as everything remains vector and therefore the best possible quality. In addition, Illustrator (and InDesign) allow for much more powerful text editing over Photoshop.
Open Illustrator, create a New Document and add your desired text using a well designed typeface. For this example, I have chosen the RipeType logo, which uses the Ripe family.
Once you have added your text, select the character that you would like to change. As you can see from the image, I want to change the default lowercase “y” to the one with a loop in the descender.
From the top menu, click the “Type” menu item, then click the “Glyphs” submenu item. This will open the Glyphs window.
In the Glyphs window, find the character that you want, and double click it to insert it. Because the “y” is selected in your text area, it will replace it with the new character.
The end result shows exactly want we wanted to achieve with the RipeType logo.
In closing, Glyphs are a very powerful typographic feature, especially for titles and logotypes so try it out for yourself, some fonts contain wonderful surprises! Enjoy!