How to set default save folder in Gimp

There does not appear to be a direct method to do this with Gimp but there is an acceptable work-around that may be enough for you. Use the following 3 steps:

1. Export the Image. First use the 'Export Image' as usual:

2. Set your preferred location. Next navigate to your preferred location and then use the '+' key at the bottom left of the screen to set this location permanently in the Gimp preferences. In my example here I am using ~/test:

3. Export your next image. Next time you Export an image you will see your desired location in an easily accessible, single click location:

Not perhaps a perfect solution but this will hopefully fulfil your needs...