Gayle, to get the sound to the back you may want to add some back fill speakers..ceiling speakers that have a separate amp with a delay to allow for the time it will take for the main sound to get back to the fill position. I found that this is very effective in low ceiling rooms.
If you have a tall ceiling then a small line array may do the job from the front. The idea is to have even coverage and spl in all areas of the room.

Normal levels for worship are around 90-94 db and for teaching 72-76 db. Maintaining those levels is the sound persons gig. Many fellowships have worship teams that play at stage levels so high that the main pa is not even needed to reach the 94 db point. In this case the best way to lower the stage level is to remove all of the speakers and amps on stage and use In Ear Monitor systems. These allow the musicians to hear what they want and the sound person to be able to mix for the best sound out front.

Raising the speakers is the first step in getting them to be able to project past the first few rows. Best results will be if they are up and angled down so that the horn is aimed at the chairs 3/4 of the way back. This is to prevent the high frequencies from bouncing off the back walls creating a slap echo. If additional coverage is need in the back then it would be beneficial to use the ceiling speaker and delayed amp scenario.

With a simple mixer there is not much to do other than set the levels and tone. Good microphones and DI boxes will help the sound quality. Do not over eq if the unit has a master eq. These types of eq are usually very broad band so using them as feedback filters results in drastic changes in the tone of the system.....the more you use the worse it sounds!

If you have feedback problems the back fill speakers will all you to run the main system a bit lower up front and the IEM system eliminates monitor feedback.

Let me know if you or the worship team have questions...this is a common situation that can be improved!


Blessing
Jeff Gefke