As I said, and as it is stated in the What is new section:MMFrLife wrote:I believe there may be a bug.
" * Removed: many redundant presets to allow faster work, but many presets now have doubled function using the new groups with radio buttons; e.g. almost all "Copy..." presets could work as old "Assign..." or "Append..." presets;"
So, if you choose Append option, you will append the part of source field to the destination field. However, if you choose Assign option, you will overwrite the destination field with the same part of the source field.
If you choose Append option, you could specify Separator which will be inserted between the old content of the destination field and the appended part from the source field, but only if both of them are non-empty. This is intended behavior. If you choose Assign option, you could choose "Copy entire field if it doesn't contain specified strings" option which is self-explanatory, I suppose. Is this the answer to your question?
By the way, there is the very detailed Description field for every preset giving examples with preset's arguments. Also, you could choose the Tune option from the Preset Settings dialog box to get the same adjustment dialog without starting execution of the preset from the menu/tooolbar. I am pretty sure that you know all that, but just to mention.
Now, could you tell me exactly when there is a bug? Some examples, please?