How to get lava bottle

Using "Player right clicks with item" global trigger:

1. Check if the player is holding a glass bottle, only proceed with the rest of the method if this is true, else do nothing.
2. Create 3 local number variables, [x], [y], and [z]. Set them to "Look [x/y/z] position of [event entity] with raytrace distance..."
3. Set the raytrace distance to the reach distance of the player (from memory it should be 4?) and set fluid mode to
    SOURCE_ONLY or ANY, depending on whether you want to target only lava sources or lava regardless of slope level.
4. If {Get block at [x], [y], [z] == [Lava Still]} (For SOURCE_ONLY)
    If {Get block at [x], [y], [z] == [Lava]} (For ANY)
    Remove block at [x], [y], [z] (Skip if you dont want to remove the lava)
    Remove 1 glass bottle from the inventory event entity
    Add 1 lava bottle to inventory of event entity

Let me know if there are any issues; this was working for me!

To create a variable at left of your mcreator app there is a place that says "Variables" just click that and you can create your variables. Here are information about their types and usage - https://mcreator.net/wiki/variables

As for "Set local block" you could probably type it in search bar in procedures or just check every single procedure blocks tbh