If you want to change fonts of IMs in Skype, it’s simple. Just sign in to Skype account, select Tools > Options from the menu bar, click IM & SMS and select IM appearancefrom the left panel, finally click Change fontto change the font.

If it was not enough to understand how to change fonts in Skype IMs, let us go in more detail with visual screenshots.
 

Step by Step with Screenshots:

1. Sign in to your Skype account with username and password.

2. You will see the main menu bar at the top with various options of drop down menu namely Skype, Contacts, Conversation, Call, View, Tools and Help.
   
   
    

3. Take you mouse to the option Tools to open a drop down menu same as given below and select the last options says Options…
   
   
    

4. Now from various options given at the left panel, select IM & SMS and select IM appearanceas given below.
   
   
    

5. You can see the button at right window of IM appearance panel namely, click it to open following window.
   
   

Here you can change font, font style and size of your font appears in IMs (Instant Messages) and click OK. These changings are only applied to your Skype displays, as for the contact you are conversing, if you send message to your Skype contact, he/she may receive in the font that they have set for his/her Skype account.