All the instructions you have posted are for Opera web browser. I have a separate application called Opera Mail version 1.0 build 1044. Thanks.

When I respond to emails, they are automatically shown in very small font (html) mode. How can I increase the font size? I have tried all the settings, and still no effect.

No, it's much smaller than original message..

I am having problem configuring Opera Mail. When I reply to messages in the html mode, they are created using very small fonts. I tried to change the font size for email compose, but it has no effect. How can I compose the email in a larger font? Thanks