De FAQ do w3m :
w3m starts with black characters on black background. How do I change this?
When compiled with colour support, w3m assumes a white background and therefore displays black characters. You may either change the background colour of your terminal (e.g. with the -bg option in a xterm) or take these steps: invoke w3m with 'w3m -M' (for monochrome), type 'o' for getting to the options screen Mark 'Display with colour' as ON and choose an arbitrary colour. Click on [OK].
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How do I change the colour of anchor-/image-/form links?
Type 'o' within w3m to get the 'options' screen. You can change these settings there.