I am trying to make a video consisting of a series of audio clips with an image showing for the duration of the video but the image only shows for less than a second
Less than a second? That's odd - the default length of an image on a Timeline is 150 frames.
Anyways, two options here. First, for images on a Timeline, move the cursor to an edge of the image's block, when the cursor changes to a "}" shape, click and hold the left mouse button, then drag out the block to the new duration.
At the top left of the interface if you click on File then "Options" in the drop down menu you'll be able to change the default length of pictures on the Timeline. This is in FRAMES, so, for a specific duration multiply time (in seconds) by frames per second of the project. Simple example, 10 seconds is 240 frames at 24fps, 250 frames at 25fps 300 frames at 30fps or 600 frames at 60fps.
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