HLT water adding additions.

I searched, forgive me if this has been answered before. I have a 15 gallon HLT that has a coil in it for the wart (wort and boil are also 15 gallons). I have my mash equipment profile set to all grain large 15 gallon stainless with a batch volume of 5 gallons. I have added my local water parameters to ingredients -> water. In my recipe I have my mash set to single infusion full body batch sparge. I will fill my HLT with 12 gallons, I use about 4 gallons for the wort, are 3 gallons or so for the rinse - > boil pot. I need the extra gallons to keep the level above the coil in the HLT to keep the temperature for the wort. My issue is (sorry it took so long) is that in my recipe, when I add my water  I choose my water profile which asks for 8.10 gallons. I then click on my water and change it to 12 gallons. I then choose my target profile. Whether I choose 8.10 or 12 or any other volume it doesn't change my water adjustment salts. Even if I delete all the adjustments and change the volume in the water profile again. Some of the recipes asks me to add salts to the water prep, then the mash. Or to the water prep then the boil. If the the salts are not changing for the water prep then obviously my water parameters are off. What am I missing?

Your water parameters are not off.  The present calculation of the program uses the amount of water demanded for the recipe and not the amount of water added to the recipe.  In this, it will not account for additional water prepared for situations such as yours where additional water is prepared. 

One of the things, if you want to rely on the program to calculate your water agent additions, you can do is add all the water agents to the mash and then add it into the mash tun when you draw the water from the HLT into the mash tun.  This will not adjust the sparge water amount, but without knowing your water chemistry (mostly your total alkalinity) it is difficult to determine what complications you might run into.

The other option is to calculate the increase in water agents needed to account for the additional water heated by hand.

Is there a way to exclude the added salts to the water prep and just add for the mash and boil? It would be better if the software could do the math for me  .

Yes you can.  On the water tab, underneath the water agent additions is a box titled 'Don't Include Water Salts'.  Click on this and the recipe and mineral additions will not change, but it will remove the water agent additions from the calculation of estimated mash pH and you can add the salts directly to the boil.  They will, however, still be marked as "mash" or "sparge" additions in your recipe.

Hope I'm not being a pest -- it seems that checking off Hold Sparge Salts until Boil did the trick -- I click it on and off and it made a difference between the mash and the boil - which will work.  Seems odd you can change the volume in the water profile and it has no effect on the water adjustment salts -- why bother having it as an option under the water profile?  Has this been brought up before for others who are using a rims system?