To apply the effect means to make it a part of the track permanently. There's no backing up and changing your mind with this route. It's called "destructive editing", meaning it permanently destroys the original wave and replaces it with the effected wave.
Perhaps what you want is to simply have the effect on the track output so you can hear it. (such as reverb or EQ) This is the recommended way to do it. Although both have a purpose and reason. To get the effect to work, simply insert it into the FX bin of the audio track.
Be sure it's an audio track and the FX is audio track FX. As soon as you insert it, you should be able to hear that effect if it's an EQ or reverb. Compression not necessarily so easy to hear at times. That's all that's to getting the FX to work. You can save the settings and adjustments you make to the FX as a new preset, and you can remove it and go back to the dry track and insert a new FX. In addition, you can insert multiple FX into any given FX bin. At times I have EQ, Reverb, and perhaps several other FX modules in the FX bin of a given track or BUSS. Yes, you can do the same thing with busses to save the number of active FX modules running in the DAW at any given time.
If you process audio, you are applying that effect permanently and destructively to the wave in the track. Once you save it and close the program, that change or application of the FX will be impossible to remove. It's only a good idea to do this if you are absolutely, positively, 100% sure about the FX. Even so, it's always a good idea to close the track BEFORE you apply the track in the event that 2 days later you don't like the fx and want to change it or remove it.
My process..... record all tracks totally dry. Add the FX as needed in the tracks or the busses and also the mastering FX into the master buss. That gives me the option to change things if I need to do so.
post edited by Guitarhacker - 2016/08/01 09:04:37