Good evening Lindsey and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
Both of these CSS rules look great.
Can you tell me where you are placing them ?
Typically you add the CSS rules to your style.css file or in your Custom CSS metabox.
Something else worth trying is adding the !important argument.
Here is an example of that
.single-tribe_events .tribe-events-single-event-title {
font-size: 2.4em !important;
}
As a first troubleshooting step, could you please provide us with your complete system information in a private reply using the instructions found in the following link?
https://theeventscalendar.com/knowledgebase/sharing-sys-info/
Let me know how that goes.
Best regards,
Geoff B.