Change volume in one clip

Win 7 64 bit - Audacity 2.1.1

I made one mp3 from three mp3 by cutting out and pasting relevant sections. Clip one and two are OK. Clip three is a bit low. Can i increase volume slightly on clip three only. They are not music they are spoken narration

After the clips are combined, use the [u]Envelope Tool[/u] to adjust one (or more) part of the recording.

Thanks. I had to start again and it worked OK. I could not raise the volume with the envelope tool

You have to zoom-out on the vertical (amplitude/volume) scale to do that : place the cursor somewhere on the vertical scale, (it will become a magnifying-glass icon) , then click on the right-hand mouse-button.
The vertical scale now extends from +2 to -2 , ( rather than +1 to -1 ), allowing you to raise (amplify) using the envelope tool , rather than just make sections quieter.

The other method is to raise the inner envelope points (second and third from the top).