Is there any way to keep the same default effect, instead of the last one used? I haven't figured out what switches it to the last one used because it doesn't do it all the time, but when it does, it causes needless clicks to revert it. The way I use it, the last effect used is almost never the next one to be used, but rather it is more likely to be a fixed default. I usually start with "burn" and adjust from there.
This was baffling me as well, since you'd think setting the check mark to the left of the preset would do it. I'm using Windows.
In my case, each time I used the effect from one image to the next, it did not even default to what I last used, but was defaulting to something else, perhaps from a previous session. I also noticed that the check marked preset kept changing to something other than what I had just last changed it to.
I found out on my own that if I held down the CTRL key while clicking to the left of the desired preset (to set the check) worked.