How do I alter a file's "kind" attribute?

Hi,

I've been looking all over for an answer to this issue, including this forum and including calling apple technical support (who couldn't help because it wasn't a software issue), so I have had no luck. I really hope somebody here can help me!!

I have many files, each with the .dat extension. But the file "kinds" for these files are all different: textedit document, text, xcode etc This means that they are all treated differently by the system, and (importantly for me) quicklook. (They also indicate this by having different icons).

This has knockon effects with different software I use them with, and it's really slowing down my workflow.

I need a way to tell OSX "all files with the .dat extension have the file kind "text' " or something to that effect.

• Checking in "Get Info" shows the files kind, but has no way to edit it.
• I have tried changing the software used to open the files (in Get Info, apply as default etc) - so for example making all .dat files open in textedit - their 'kind' remains the same (whatever it was before I tried doing it).
• I have tried opening the files in textedit (for example) and saving them again - their kind remains the same.
• I have tried creating a new file in xcode with the .dat extension (it just says it is a textedit file).
• I actually have no idea how I created the file with the 'text' file type now - this is the only one which is viewable in quicklook.

I have hundreds (literally) of these .dat files, I really need a way to use them with quicklook, ie I just need to change their kind to "text".

Any help would be much appreciated... I'm going round in circles here...

Many thanks!