The options available to you depend on the e-book platform and sometimes on individual titles.
Some platforms such as VLEBooks have Read Online options and colour overlays. More info about e-book accessibility features is on our e-book accessibility guide.
UAL computers have assistive technology, such as Claro Read, which has a screen ruler and colour overlays. For more information check UAL assistive technology webpage.
Alternatively, download a book chapter as PDF and convert it to Microsoft Word using SensusAccess. Then you can change the background colour in Word.