Jimmers,
I have a Timex Ironman Flix too.
If I understand your question ...
1)Set watch to CHRONO mode and press start/split key and run your 1st 400m.
You should see small number at top (split) and larger number (total) going up in phase.
2)At end of first 400m, press start/split key again.
Everything will freeze for about 10 seconds and you can see your time for 400m.
After 10 seconds, the displays will be incrementing again - large number showing total time, smaller top number showing time for your new lap.
3) AT end of this 400m, press start/split key again and same as above (2) will happen.
Now, while you're running your third 400m, if you want to see your splits so far - press RECALL key 4 times. It will scroll through Total/Avg/Best and finally will show you your previous 400m split times in the small numbers at the top of the display - starting with previous lap and going backwards to first lap.
To return to current times, press SET key or, if you don't press anything for a while, it will return to CHRONO mode on its own.
I know it sounds complicated, but try it and see.
Cheers
Bruxy