Text formatting has its own ideas

Save the format, close it and open it again and change it back to the original format, s there any workaround.
English is not good, machine translation has something wrong with it, please forgive me.

Can you tell us specific steps that produce the problem? For example, you might select a word, and then put it in italics, and then etcetera.

It would be helpful to know what formatting in particular is lost.

Also, if this happened when you closed the project and reopened it, you need to be sure you are opening the very same version of the project. When testing again, do not use the Recents menu to open or reopen the project. Find your project in the Finder and open it (double-click) directly from the Finder.