Readability problems

On my small 10.1 screen in a number of situations I am finding the text difficult to read, sometimes because of the size of the font, more often it is the colour of the font against the background. This applies to some apps and often with system popup windows. I have just seen an example of pale green on white but frequently text is pale grey or pale blue on a white background. Rather than the colour itself is a combination of how intense it is and the background. If I could I would ban all pale shade text from my machine. I am experimenting with dark mode, which again only helps sometimes, and sometimes I find it is better off rather than on.

I have tried making changes in Settings without success. I have a small app called A+Text Change Size which works in some situations but not others. Zoom and the Magnifier can be used. But I would prefer to have the text displayed clearly in the first place. Suggestions?

Thanks, there are a number of things here to try, plus I rather like the effect of the pale yellow background so I might use that too.

I think I have been making a fundamental mistake, I assumed that I was able to change fonts just by using what is shown in Settings (to me what is shown there implies this). But when I select a new font including bold, it is not shown in the preview box. No changes are shown there. I assumed maybe all that was needed was to restart. I now see that there is still no change. From the Tutorials I see that much more is involved, including Registry changes, something I normally steer clear of.

Despite this I have downloaded the reg file from the the Tutorial and saved it to Desktop. I have got as far as this in the past when enabling Timeline (as it did not work at first) but I see there is a stage before Merging, namely Unblock and Edit --- which is where I am stuck. (a) I don't see how to Unblock and (b) if I click Edit I just get an extract from the Tutorial, not what I think should appear.

Can you advise me what to do next please? I am anxious not to mess things up.