Sometimes, you might feel it's hard to translate within SDL Trados Studio due to small text size. In the Options menu, you can change the font settings in Editor.
Please God to "Tools > Options" and choose "Editor" and then "Font Adaptation" where you can make changes as you wish.
If you still feel that the font size is too small, please consider changing the formatting display style. To do this, please go to "Tools > Options" and choose "Editor." In the "Formatting display style" section, you can change the style. (For example, you can disable formatting by selecting "Show all tags but do not show formatting."
Also, you can change the font size in the Translation Results Window ("Editor > Translation Results Windows.")