To reload them click on Palettes, then click on Load a Palette or Load an Opacity Table. Fixed palettes and tables can also be loaded from the Fixed menu. Click on Windows, click on Palette Editor. Palette editor window opens. Current palette is shown along top.
Controls are on right.
Then use the mouse to redraw the chosen color in the edit window. Palette will be updated along top. Palette will be applied to image after it is rendered again. To change the opacity, turn all the colors off and the alpha on, then redraw the alpha line. Use the left and right mouse buttons to move and limit the usable area of the palette by moving the thin, red line at the top of the edit window just below the current palette display.