Increasing Hot Water flow in Shower
I am in a 4 year old home. The County Inspectors had done something in the kids' bath that only allowed lukewarm water to flow in the shower. Understand that this was done to prevent scalding water to flow on to the kids. I believe this is something to do with the Flow Valve or Cartridge or something else. How can I access this and make adjustments such that there is a reasonable flow of hot water.
The shower has a single control for hot and cold water.
The forum has 2 other questions that are similar to this but a clear answer could not be found.
Is this something I can do (a novice) or should I call a plumber? All other baths in the house has acceptable hot water flowing when the shower control is turned to hot.
Thanks in advance