Is there a way to change effects with a Next and Last option In order to preview effects one after another?

You can use direct selects to select your effects.

If you have your effects on direct selects, you could write a macro that stops the effect and then waits for you to select or type the next effect you want to run. Could look like this:

Line 1: [Select Last] [Effect] [Enter]

***if you have effects on direct selects***

Line 2: [Select Last] 

And then you would select the effect direct select that you want to run.

***if you want to manually type the effect number***

Line 2: [Select Last] [Effect]

And then you would type the effect number followed by [Enter]

The other option I can think of is make a macro for every single effect that would stop the current effect and then apply the desired effect. Could look something like this:

Line 1: [Select Last] [Effect] [Enter]

Line 2: [Select Last] [Effect] (effect #) [Enter]

However, that would be a lot of macros that only have 1 function each which isn't very practical and would take a lot of work to write, and thus probably not be worth the hassle.

Mr. Nowlin, thank you! 

I created the Macro from your first suggestion above, which I labeled FX Next.

      Line 1:   [Select Last] [Effect]

      Line 2:   [Select Last] 

Then I added it to a Custom DS screen.

 I can now select an Effect from my Effects DS, preview it, and then select the Macro (FX Next) to terminate the running effect. Then I can select the next Effect I want to preview from my DS screen. This makes quickly previewing Effects very efficient. Thanx again! 

Mr. Nowlin, thank you! 

I created the Macro from your first suggestion above, which I labeled FX Next.

      Line 1:   [Select Last] [Effect]

      Line 2:   [Select Last] 

Then I added it to a Custom DS screen.

 I can now select an Effect from my Effects DS, preview it, and then select the Macro (FX Next) to terminate the running effect. Then I can select the next Effect I want to preview from my DS screen. This makes quickly previewing Effects very efficient. Thanx again! 

Absolutely! Glad I was able to help out!