You can format your mash so date and captions don't overlap with the TikTok/Instagram watermark and orientation.
This is currently available on the iOS app only.
On the iOS app:
If you want to set the date/caption placement to the classic 1SE style, follow these steps:
Open the mashing screen.
Tap "Classic" to set the placement to the lower left bottom of your video.
If you wish to format it back for TikTok or Instagram Reels, tap on "Default".