Issue with having both slow fall and levitation

I'm trying to make Blaze armor: I have a command block giving me levitation 253, essentially slow falling while wearing. However, I would like to change the amplifier to 1 (so the player floats up) temporarily as long as the player is holding a blaze rod. But the two commands do not seem to mix; the amplifier of 1 won't overwrite the 255.

Here's what I have now:

If wearing the Blaze armor: /effect @p 25 3600 253 true

If holding the Blaze rod: /effect @p 25 3600 1 true

What am I doing wrong?

This is intended, only stronger effects overwrite weaker ones. You need to clear the stronger one if you want to instantly apply the weaker one.

Also, your command syntax is wrong in the question, but probably not in the game (otherwise you would have gotten an error message). Please copy-paste your commands in the future, instead of manually re-typing them, because errors like this can happen then.

I was trying to make Blaze armor but no one helped so I figured it out myself. While wearing the gear, I had one command block giving me levitation 253, (essentially slow falling while wearing) then while holding a blaze rod, I had to remove the amplifier and add and new amplifier of 1 (so the player floats up). The amplifier of 1 won't overwrite the 255, so you have to remove the 255 and add a completely new effect.

If wearing the Blaze armor: /effect @p 25 3600 253 true

If holding the Blaze rod: /effect @p 25 3600 1 true