I think it can be done, but there's a lot of trial and error involved. One of the ways that might work, would be as follows:
Go to Control Panel, Appearance and Personalization, click on "Change window glass colors"
Under Personalization, click on "Advanced appearance settings." This will get you to the Windows Color and Appearance dialog.
Click on Advanced, and in the 'Item' list, select the item in Windows that you want to change the font for.
This is where the trial and error comes in because I don't know exactly which Item controls the font/boldness for the Start Button popup. So you'd probably have to check each Item. For example, if you want to change the Icon font, click Icon in the list. Then, make any of the following changes:
In the Font list, click the font that you want to use.
In the Size list, click the font size that you want.
In the Color list, click the font color that you want.
(Note: Some of the Items in the list do not
of the above options.)
Repeat these steps for each item that you want to make changes to, click OK, and then click OK again.
Here's some additional help from our tutorials: Fonts - Change