I have found a workaround for Windows. Please be warned that if are not computer savy, please do not do this!!! This is a hack, so use this at your own risk! I am not responsible for any damage that may result from this hack, so please only follow this if you are willing to accept the risk!!
Here is what i did:
1. I backed up the content of this registry location first:
namely (Default) and Path
2. Update the (Default) to point to your preferred browser's executable.
Update Path as the path to your preferred browser. Not sure if it is necessary, but i ended the path with ;
3. Fire up Ufile and do your Auto-fill. (No instance of your preferred browser should be opened, else it will complain)
4. Restore the original values in the registry once you are done.
I hope this instruction is clear for all you "hackers" out there.
For those who are not, sorry...i wish there was an easier solution.