eM Client ignoring font and signature preferences?

I just started using eM Client yesterday, and I’ve had a persistent issue: The settings save my preferences for fonts but new messages still use the old default font.

I changed the font from Times New Roman to Avenir LT Standard 45 Book for both reading and composing. I’ve done it SEVERAL times now, and I’ve restarted the app several times as well as my computer. Those changes appear correctly within the settings, but whenever I start a new message, it reverts to Times New Roman. I’m unable to manually change the font within the message, as well. 

Possibly related: I’ve set a default signature to be used on all messages. After I restart eM Client, the signature doesn’t appear always automatically. I can add it using the dropdown in the compose window. The settings window shows the default signature for new mail, replies, and forwards, but it doesn’t seem to have worked.

I’ve checked the Errors window under Operations, and it’s empty. The log shows only syncs.

I’m running version 7.2.34959.0 on Windows 10 Pro (version 1803, build 17123.648). The email account in question is a Gmail account.

You may want to check that you are not composing the message in plain text.

To change the default setting go to Menu > Tools > Settings > Mail > Compose > Mail Format.

Make sure it is set to HTML, then save your settings and try again with composing a new message.