To edit multiple images at once, you need to create a batch. You can then use the Batch Editor to make the changes.
Steps (iOS)
To create a batch of images:
Select the Space you want to work in.
Select Batch.
Select Start new batch.
Alternatively, select Resume previous batch to continue with your last batch. Photoroom opens it in the Batch Editor, and you can skip the remaining steps.
Select the images you want to include in your batch and select the checkmark icon to confirm.
Photoroom creates your batch and each image keeps its original background. A Templates panel appears at the bottom.
Either:
Select X on the Templates panel to close it without using a template. Your batch images will keep their original background.
Select a template. When you choose a template, Photoroom applies the design from the template to your batch images. This may replace the background and add other layers.
You have now created a batch. The images appear in a grid in the Batch Editor and you can use the Batch Editor features to make changes to the images. For details, see Edit multiple images at once in Batch - workflow (iOS).