Niagara temporary variables and setting variables

Hello, I’m trying to make a temp variable and set it like in this old video 59:46 but I’m unable to recreate this with a “Temp” parameter. Only if I use “Particle.” instead of “Temp.” I’m not sure why this is.

To break down my question further:
First of, if I write "set variable " after clicking the plus button next to Particle Update, I get no results, so what should I be writing if not the name of the module? If for example I make a variable, I am able to set the variable by using my mouse to drag it under Particle Update, then it will make a Set Variables module. However, if I click that plus button and I write “set” my variable doesn’t show up, I unticked “library only” and still nothing, so what should I be writing?
Why is this? Am I doing something wrong or has Niagara changed since then and theres a new way (or no way?) to do it?
Is there a video or training I can watch which covers this? I get how I can plug variables into existing stuff, but I don’t understand how to set them and what / how temp variables work.

It seems to be because I wasn’t doing it the right way. the solution seems to be to click the plus button next to Particle Update or w/e in the selection window, then write the variable data type, e.g. vector2D, this lets me create a variable and put “temp.” as prefix

Originally I was trying to do it by creating the variable in the parameters window, doing it that way I have no idea how to then set it with a set variables module