Lost Mail preview pane OS Catalina 10.15.5

hi, just noticed that after a recent update i've lost a couple of settings in Mail.

1. new messages are shown in bold but no longer change when i click on them (unbold). i have to actually open the message now for it to unbold. cant' seem to find a setting to change this. the only setting option is to show unread messages in bold.
2. i no longer have a preview pane below my inbox messages. selecting 'choose side preview does not give me a side preview pane and deselecting that option does not give me the bottom preview pane.

any advice would be appreciated!!