Here is a trick to solve your problem.
From the top menu, go to Raster>Conversion>Translate.
Then, in the Translate window, perform the following tasks:
- Select your input layer.
- Select the output path and write an output file name.
- Choose target SRS (desired output coordinate reference system).
- After performing the above steps, you will see the command at the bottom (inside a text box).
- Edit this command, and add "-b 1" at the end if you want to extract the first band from the input image. Add "-b 2" if you want to extract the second band, and so on.
For example (To extract the first band):
gdal_translate -of GTiff "path of input image" "path of output image" -b 1
For example (To extract the first two bands):
gdal_translate -of GTiff "path of input image" "path of output image" -b 1 -b 2
In this way, you can extract different bands and their combinations from an input image.
For more description, visit the documentation.