The default of an axes works exactly as you have defined it:
figure; axes;
set(gca, 'DefaultTextFontSize', 35)
text(0.5, 0.5, 'Hello')
The default of a figure:
figure('DefaultTextFontSize', 35);
axes;
text(0.5, 0.5, 'hello')
The default of all figures:
set(groot, 'DefaultTextFontSize', 35);
figure; axes;
text(0.5, 0.5, 'hello')
So the actual problem is hidden in:
"but these don't seem to be working well for me."
Please explain, why you are not satisfied with these working methods. Perhaps you do not want to modify the default text font size, but the size of the axes lables or tick marks?
