Want PGN layers to be centered when exporting

 File >> Export >> Layers to file

Trim layers is probably what you need on, or possibly the off as your 2nd paragraph seems to ask for the opposite.

@j24013432kha8 

It's not really clear what you are asking, and I see that your question has been here for two days.

PNGs do not support layers, so if you export to PNG there will not be multiple layers in the file. I wonder if you might mean that you have PNGs and are trying to copy (not export) and center them into another file?

• If this is what you mean, hold down the Shift key as you drag and drop to center one image onto another
  
  
• If it is not what you mean, please clarify.
  When you use the word "export", what are you starting with and what are your steps to do the export?
  Are the images in separate files and need to be combined?
  What format are you saving the new file to? Both TIFF and PSD support layers. PNG and JPEG do not.

Also, if the images are already layers in a new document, did you try multiple selecting the layers in the Layers panel and using the Alignment buttons in the options bar for the Move tool?

Share screen shots if you think it will help. Use the Insert Image button ( mountain and sun).

Jane