Could you please let us know what subscription option they use? There are three subscription options and neither of them redirects to Subscription page. If user is not activated subscription via email and  he/she goes to own subscription page, he/she see "No subscriptions found for this member. " message:

When user subscribe to a forum or a topic, they are being notified that they should check the email:

thanks for your answer.

indeed, there is a notification which shows the member that he has to check his email.

But the notification stays on screen only 2 seconds... so sometimes, the member can not see it.

Hello,

Could help me to find how to modify the folowing message, which appears just after subscription ?

"No subscriptions found for this mumber"

My members tell me it is really not easy to subscribe on this forum.

Thanks.

My members tell me it is really not easy to subscribe on this forum.

I can't understand why that's not easy to subscribe. I think the member who says this has minimum skills in inet and in discussions. You just need to check the checkbox or click on the subscription button. I don't think there is easier way to subscribe in web. Please read the doc and explain your members how it's easy:

https://wpforo.com/docs/root/members/member-subscriptions-page/

wpForo even has an option to subscribe users automatically, they just need to post or create a topic.

Also, maybe some of your users are potential spammers and they don't want to confirm their subscriptions via email. In this case just navigate to Dashboard > Forums > Features admin page find the "Enable Subscription Confirmation" option and set it  "No". So your users will subscribe very easy without subscription confirmation.