You can change the font size of a visual easily by going to the format option of that. However, if you want to change it for multiple visuals, better to use Themes for it. Recently Power BI Desktop came up with some easy-to-use options to customize your theme. That means you can now easily increase the font size for your Power BI file (all visuals, and pages) with just a few clicks. no need to worry about JSON files etc. This is what I am going to explain in this post.
Download the Most Recent Version of Power BI Desktop
If you already don’t have the most recent version of Power BI Desktop, then download it. In the Help tab, under About, you would be able to see what is your current version of Power BI Desktop;
If you have installed the Power BI Desktop app from the Microsoft Windows Store on your Windows 10, then it gets automatically updated.
Enable the Customize Theme Feature
As of right now, the customize theme feature is a preview feature, and you should enable it, by going to File -> Options and Settings -> Options, and then under Preview Features, make sure you select that option;
Note that, this feature will be out of preview and generally available probably in the next few months after the publish date of this article, so you might not need this step of enabling the preview feature anymore if you are visiting this post in the future.
Another preview option I recommend to enable is the Update Ribbon, that way, you can see the Power BI desktop with the new layout (similar to the screenshots of this post).
Customize the Current Theme
After setting up the preview features (and re-starting the Power BI Desktop), you can go to the View tab. Here is where you can choose a different theme, or even customize the existing one:
The Customize theme windows is a very simple configuration window, you can go to the Text tab, and configure whatever you want. There is much more than just text in the theme, like colors, and other stuff. make sure to check those out too.
for some of the reports that you have created previously with the default or custom theme, you might see an error saying that this setting cannot be applied on those themes, you can then select another Theme from the list, and would be able to continue with the text formatting. Here you can see all the font sizes changes in my report with this configuration;
Here is a look at how you can change colors too;
Re-Use your Theme
As you see it is easy to set up a theme. However, it is also easy to set up inconsistent themes in each Power BI file. My recommendation is to set it up in one file and then export it. This will give you a JSON data type file.
And then in other Power BI files, you can just Browse for that theme. It is good to keep that theme in a shared folder that other Power BI developers have access to it too.