Not at my computer with the Daz installation atm., but let's see.
There are to ways to change the direction of your texture, one inside and one outside of Daz, assuming you do your shading by just clicking in a shader preset, which uses seamless tiles for all related maps.
Are you already familiar with the "Surface Editor" tab ?
If not here is a video (with an older Daz version) about how it works: https://www.youtube.com/watch?v=PzUajlRhJfU
The main thing is around 3:06, it shows the dialog you get when you click on an image in your shader, in Daz 4.9 there are more options than that and one is called Layered Image Editor, if you click it a window opens where you can i.a. rotate the map/ image which is used in this certain property of the shader.
The main map for the texture is in the Diffuse Color or Normal Color Property, depending on the shader you use, but all the other maps are important too.
Daz then makes a temporary rotated copy of your original texture and uses this instead, do this for every single map/ image like color, normal etc. which is used for this certain surface (that varies, use scroll and take a look in which properties are images) and you'll be fine.
Outside of Daz you can do it by rotate the image in an image editing program like PS or Gimp, find out where your textures maps are located, e.g. by clicking browse like shown in the video, open the images in your image editor and just make 90° rotated copies of your texture maps and store it in the same diretory.
Then again use browse for every property of your shader that has a map/ image and use your rotated copies instead.
Be careful to not damage or overwrite your original maps/ images when you do it the second way...!