The Per-Preset function is a great feature and exactly for what you're wanting to do. I use a combination of Global switches and Per-Preset switches. The Global switches are assigned to effects and functions that I use in every preset, Per-Preset for all others.
Unlike the global switches, you will need to save any changes to the Per-Preset switches
First, there are two methods for the Per-Preset function:
1. Per-Preset Placeholder. These reserve switches for the Per-Preset function and can be assigned different effects or functions needed in different presets.
2. Per-Preset Overrides. These allow you to assign different effects or functions to a global switch.
Per-Preset Placeholders sound like what you're looking for and the way I typically use them.
To assign a switch as a Placeholder:
- Select the switch you want to use.
- Select 'Per-Preset' from the <Category> list.
- Select the PP# for the switch. I started with PP# 1 and continued in order for each additional switch.
Once you have the Placeholders assigned, you're now ready to use them as you need in different presets. To assign an effect or function to a Per-Preset switch, click on <FC Per-PRST> button at the top left in FM9 Edit, click on the PP# you want to use and assign the effect or function as you would a global switch in the FC Edit page.
Per-Preset Overrides are great if there's an effect/function in one Layout that you need quicker access to in a different layout. This can be done in either the <FC Edit> or <FC Per-Prst> view.
For example, Per-Preset #5 switch controls Reverb 2 in Layout 4 but you would like it in Layout 3. In Layout 3, there's a Delay block on switch 4 that you're not going to change at any point in the song so you would add the Per-Preset Override to assign PP#5 to switch 4 in Layout 3.
To assign the Override in this scenario:
- Select the switch you want to override
- Click on the <PER-PRESET OVERRIDE> window
- Select 'PP#5'
When you assign a Per-Preset Override, you will see a warning in the Functions window. This is just alerting you that the override has been assigned to the switch.
Here's a video by Rosh Roslin that goes through the process, it starts @4:40.