During launch, the g-force felt by the crew is directly back toward the engines and maxed out at about 3g. During reentry, it also maxed out at about 3g, but pointed at about a 45 degree angle down toward the heat shield. Were the seats configured such that the crew could take both of these acceleration loads equally well, or did they sit differently between launch and reentry? How were the potential g-forces in an abort scenario handled?
The seats had a back angle adjustment that was changed from the ascent position for entry. Disappointingly, this is not mentioned in the press reference manual (https://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_coord.html) but you can read about the other seat adjustments there.
This excerpt from the Shuttle Crew Escape Training Manual describes the different settings.